21156772807 has 2 divisors, whose sum is σ = 21156772808. Its totient is φ = 21156772806.

The previous prime is 21156772787. The next prime is 21156772831. The reversal of 21156772807 is 70827765112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21156772807 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21156775807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578386403 + 10578386404.

It is an arithmetic number, because the mean of its divisors is an integer number (10578386404).

Almost surely, 2^21156772807 is an apocalyptic number.

21156772807 is a deficient number, since it is larger than the sum of its proper divisors (1).

21156772807 is an equidigital number, since it uses as much as digits as its factorization.

21156772807 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 329280, while the sum is 46.

The spelling of 21156772807 in words is "twenty-one billion, one hundred fifty-six million, seven hundred seventy-two thousand, eight hundred seven".