21554656177 has 2 divisors, whose sum is σ = 21554656178. Its totient is φ = 21554656176.

The previous prime is 21554656169. The next prime is 21554656187. The reversal of 21554656177 is 77165645512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10924221361 + 10630434816 = 104519^2 + 103104^2 .

It is a cyclic number.

It is not a de Polignac number, because 21554656177 - 2³ = 21554656169 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21554656177.

It is not a weakly prime, because it can be changed into another prime (21554656127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777328088 + 10777328089.

It is an arithmetic number, because the mean of its divisors is an integer number (10777328089).

Almost surely, 2^21554656177 is an apocalyptic number.

It is an amenable number.

21554656177 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554656177 is an equidigital number, since it uses as much as digits as its factorization.

21554656177 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1764000, while the sum is 49.

The spelling of 21554656177 in words is "twenty-one billion, five hundred fifty-four million, six hundred fifty-six thousand, one hundred seventy-seven".