20931400687 has 2 divisors, whose sum is σ = 20931400688. Its totient is φ = 20931400686.

The previous prime is 20931400639. The next prime is 20931400727. The reversal of 20931400687 is 78600413902.

It is an a-pointer prime, because the next prime (20931400727) can be obtained adding 20931400687 to its sum of digits (40).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20931400687 - 2²³ = 20923012079 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20931403687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10465700343 + 10465700344.

It is an arithmetic number, because the mean of its divisors is an integer number (10465700344).

Almost surely, 2^20931400687 is an apocalyptic number.

20931400687 is a deficient number, since it is larger than the sum of its proper divisors (1).

20931400687 is an equidigital number, since it uses as much as digits as its factorization.

20931400687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 40.

The spelling of 20931400687 in words is "twenty billion, nine hundred thirty-one million, four hundred thousand, six hundred eighty-seven".