21767252657 has 2 divisors, whose sum is σ = 21767252658. Its totient is φ = 21767252656.

The previous prime is 21767252629. The next prime is 21767252681. The reversal of 21767252657 is 75625276712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15785158321 + 5982094336 = 125639^2 + 77344^2 .

It is a cyclic number.

It is not a de Polignac number, because 21767252657 - 2²⁶ = 21700143793 is a prime.

It is not a weakly prime, because it can be changed into another prime (21767252257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10883626328 + 10883626329.

It is an arithmetic number, because the mean of its divisors is an integer number (10883626329).

Almost surely, 2^21767252657 is an apocalyptic number.

It is an amenable number.

21767252657 is a deficient number, since it is larger than the sum of its proper divisors (1).

21767252657 is an equidigital number, since it uses as much as digits as its factorization.

21767252657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2469600, while the sum is 50.

The spelling of 21767252657 in words is "twenty-one billion, seven hundred sixty-seven million, two hundred fifty-two thousand, six hundred fifty-seven".