18715000921 has 2 divisors, whose sum is σ = 18715000922. Its totient is φ = 18715000920.

The previous prime is 18715000907. The next prime is 18715000943. The reversal of 18715000921 is 12900051781.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14927952400 + 3787048521 = 122180^2 + 61539^2 .

It is an emirp because it is prime and its reverse (12900051781) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18715000921 is a prime.

It is not a weakly prime, because it can be changed into another prime (18715000021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9357500460 + 9357500461.

It is an arithmetic number, because the mean of its divisors is an integer number (9357500461).

Almost surely, 2^18715000921 is an apocalyptic number.

It is an amenable number.

18715000921 is a deficient number, since it is larger than the sum of its proper divisors (1).

18715000921 is an equidigital number, since it uses as much as digits as its factorization.

18715000921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5040, while the sum is 34.

The spelling of 18715000921 in words is "eighteen billion, seven hundred fifteen million, nine hundred twenty-one", and thus it is an aban number.