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18783781 = 412411901
BaseRepresentation
bin100011110100…
…1111000100101
31022100022111121
41013221320211
514302040111
61510333541
7315442132
oct107517045
938308447
1018783781
11a66a595
12635a2b1
133b78983
1426cd589
1519b0871
hex11e9e25

18783781 has 8 divisors (see below), whose sum is σ = 19331928. Its totient is φ = 18240000.

The previous prime is 18783769. The next prime is 18783797. The reversal of 18783781 is 18738781.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 225 + 18783556 = 15^2 + 4334^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 5-Lehmer number, since φ(18783781) divides (18783781-1)5.

It is a cyclic number.

It is not a de Polignac number, because 18783781 - 25 = 18783749 is a prime.

It is a super-2 number, since 2×187837812 = 705660857311922, which contains 22 as substring.

It is a deceptive number, since it divides R18783780.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18783731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8931 + ... + 10831.

It is an arithmetic number, because the mean of its divisors is an integer number (2416491).

Almost surely, 218783781 is an apocalyptic number.

It is an amenable number.

18783781 is a deficient number, since it is larger than the sum of its proper divisors (548147).

18783781 is a wasteful number, since it uses less digits than its factorization.

18783781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2183.

The product of its digits is 75264, while the sum is 43.

The square root of 18783781 is about 4334.0259574673. The cubic root of 18783781 is about 265.8240917725.

The spelling of 18783781 in words is "eighteen million, seven hundred eighty-three thousand, seven hundred eighty-one".

Divisors: 1 41 241 1901 9881 77941 458141 18783781