21957659687 has 2 divisors, whose sum is σ = 21957659688. Its totient is φ = 21957659686.

The previous prime is 21957659683. The next prime is 21957659699. The reversal of 21957659687 is 78695675912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21957659687 - 2² = 21957659683 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21957659683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978829843 + 10978829844.

It is an arithmetic number, because the mean of its divisors is an integer number (10978829844).

Almost surely, 2^21957659687 is an apocalyptic number.

21957659687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21957659687 is an equidigital number, since it uses as much as digits as its factorization.

21957659687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 57153600, while the sum is 65.

The spelling of 21957659687 in words is "twenty-one billion, nine hundred fifty-seven million, six hundred fifty-nine thousand, six hundred eighty-seven".