21515030657 has 4 divisors (see below), whose sum is σ = 22209063936. Its totient is φ = 20820997380.

The previous prime is 21515030633. The next prime is 21515030743. The reversal of 21515030657 is 75603051512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21515030657 - 2⁸ = 21515030401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21515030617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 347016593 + ... + 347016654.

It is an arithmetic number, because the mean of its divisors is an integer number (5552265984).

Almost surely, 2^21515030657 is an apocalyptic number.

It is an amenable number.

21515030657 is a deficient number, since it is larger than the sum of its proper divisors (694033279).

21515030657 is an equidigital number, since it uses as much as digits as its factorization.

21515030657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 694033278.

The product of its (nonzero) digits is 31500, while the sum is 35.

The spelling of 21515030657 in words is "twenty-one billion, five hundred fifteen million, thirty thousand, six hundred fifty-seven".