18736621 has 4 divisors (see below), whose sum is σ = 18756412. Its totient is φ = 18716832.

The previous prime is 18736609. The next prime is 18736637. The reversal of 18736621 is 12663781.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12663781 = 13 ⋅974137.

It can be written as a sum of positive squares in 2 ways, for example, as 14976900 + 3759721 = 3870^2 + 1939^2 .

It is a cyclic number.

It is not a de Polignac number, because 18736621 - 2¹⁹ = 18212333 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18736681) 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, 8400 + ... + 10393.

It is an arithmetic number, because the mean of its divisors is an integer number (4689103).

Almost surely, 2^18736621 is an apocalyptic number.

It is an amenable number.

18736621 is a deficient number, since it is larger than the sum of its proper divisors (19791).

18736621 is an equidigital number, since it uses as much as digits as its factorization.

18736621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19790.

The product of its digits is 12096, while the sum is 34.

The square root of 18736621 is about 4328.5818693886. The cubic root of 18736621 is about 265.6014392205.

The spelling of 18736621 in words is "eighteen million, seven hundred thirty-six thousand, six hundred twenty-one".