21157607677 has 2 divisors, whose sum is σ = 21157607678. Its totient is φ = 21157607676.

The previous prime is 21157607671. The next prime is 21157607717. The reversal of 21157607677 is 77670675112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14655765721 + 6501841956 = 121061^2 + 80634^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21157607677 is a prime.

It is a super-2 number, since 2×21157607677² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21157607677.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21157607671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578803838 + 10578803839.

It is an arithmetic number, because the mean of its divisors is an integer number (10578803839).

Almost surely, 2^21157607677 is an apocalyptic number.

It is an amenable number.

21157607677 is a deficient number, since it is larger than the sum of its proper divisors (1).

21157607677 is an equidigital number, since it uses as much as digits as its factorization.

21157607677 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864360, while the sum is 49.

The spelling of 21157607677 in words is "twenty-one billion, one hundred fifty-seven million, six hundred seven thousand, six hundred seventy-seven".