18715000021 has 2 divisors, whose sum is σ = 18715000022. Its totient is φ = 18715000020.

The previous prime is 18715000009. The next prime is 18715000027. The reversal of 18715000021 is 12000051781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16768955025 + 1946044996 = 129495^2 + 44114^2 .

It is a cyclic number.

It is not a de Polignac number, because 18715000021 - 2²¹ = 18712902869 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18715000021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18715000027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9357500010 + 9357500011.

It is an arithmetic number, because the mean of its divisors is an integer number (9357500011).

Almost surely, 2^18715000021 is an apocalyptic number.

It is an amenable number.

18715000021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18715000021 is an equidigital number, since it uses as much as digits as its factorization.

18715000021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 560, while the sum is 25.

The spelling of 18715000021 in words is "eighteen billion, seven hundred fifteen million, twenty-one", and thus it is an aban number.