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18736381 = 30616121
BaseRepresentation
bin100011101111…
…0010011111101
31022020220111001
41013132103331
514244031011
61505330301
7315154006
oct107362375
938226431
1018736381
11a637a14
126336991
133b60221
1426ba1ad
1519a17c1
hex11de4fd

18736381 has 4 divisors (see below), whose sum is σ = 18745564. Its totient is φ = 18727200.

The previous prime is 18736379. The next prime is 18736387. The reversal of 18736381 is 18363781.

18736381 is a nontrivial binomial coefficient, being equal to C(6122, 2).

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 10562500 + 8173881 = 3250^2 + 2859^2 .

It is a 3-Lehmer number, since φ(18736381) divides (18736381-1)3.

It is a cyclic number.

It is not a de Polignac number, because 18736381 - 21 = 18736379 is a prime.

It is a super-2 number, since 2×187363812 = 702103945954322, which contains 22 as substring.

It is a deceptive number, since it divides R18736380.

It is a self number, because there is not a number n which added to its sum of digits gives 18736381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18736387) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1 + ... + 6121.

It is an arithmetic number, because the mean of its divisors is an integer number (4686391).

It is a Poulet number, since it divides 218736380-1.

Almost surely, 218736381 is an apocalyptic number.

18736381 is the 6121-st triangular number and also the 3061-st hexagonal number.

18736381 is the 2041-st centered nonagonal number.

It is an amenable number.

18736381 is a deficient number, since it is larger than the sum of its proper divisors (9183).

18736381 is an equidigital number, since it uses as much as digits as its factorization.

18736381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9182.

The product of its digits is 24192, while the sum is 37.

The square root of 18736381 is about 4328.5541465944. The cubic root of 18736381 is about 265.6003051737.

The spelling of 18736381 in words is "eighteen million, seven hundred thirty-six thousand, three hundred eighty-one".

Divisors: 1 3061 6121 18736381