21207956767 has 2 divisors, whose sum is σ = 21207956768. Its totient is φ = 21207956766.

The previous prime is 21207956743. The next prime is 21207956821. The reversal of 21207956767 is 76765970212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21207956767 - 2²⁷ = 21073739039 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21207996767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10603978383 + 10603978384.

It is an arithmetic number, because the mean of its divisors is an integer number (10603978384).

Almost surely, 2^21207956767 is an apocalyptic number.

21207956767 is a deficient number, since it is larger than the sum of its proper divisors (1).

21207956767 is an equidigital number, since it uses as much as digits as its factorization.

21207956767 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2222640, while the sum is 52.

The spelling of 21207956767 in words is "twenty-one billion, two hundred seven million, nine hundred fifty-six thousand, seven hundred sixty-seven".