20931407687 has 2 divisors, whose sum is σ = 20931407688. Its totient is φ = 20931407686.

The previous prime is 20931407671. The next prime is 20931407701. The reversal of 20931407687 is 78670413902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20931407687 - 2⁴ = 20931407671 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20931400687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10465703843 + 10465703844.

It is an arithmetic number, because the mean of its divisors is an integer number (10465703844).

Almost surely, 2^20931407687 is an apocalyptic number.

20931407687 is a deficient number, since it is larger than the sum of its proper divisors (1).

20931407687 is an equidigital number, since it uses as much as digits as its factorization.

20931407687 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 508032, while the sum is 47.

The spelling of 20931407687 in words is "twenty billion, nine hundred thirty-one million, four hundred seven thousand, six hundred eighty-seven".