21007005697 has 2 divisors, whose sum is σ = 21007005698. Its totient is φ = 21007005696.

The previous prime is 21007005683. The next prime is 21007005709. The reversal of 21007005697 is 79650070012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11045169216 + 9961836481 = 105096^2 + 99809^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21007005697 is a prime.

It is not a weakly prime, because it can be changed into another prime (21007405697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10503502848 + 10503502849.

It is an arithmetic number, because the mean of its divisors is an integer number (10503502849).

Almost surely, 2^21007005697 is an apocalyptic number.

It is an amenable number.

21007005697 is a deficient number, since it is larger than the sum of its proper divisors (1).

21007005697 is an equidigital number, since it uses as much as digits as its factorization.

21007005697 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26460, while the sum is 37.

The spelling of 21007005697 in words is "twenty-one billion, seven million, five thousand, six hundred ninety-seven".