21755477257 has 2 divisors, whose sum is σ = 21755477258. Its totient is φ = 21755477256.

The previous prime is 21755477213. The next prime is 21755477323. The reversal of 21755477257 is 75277455712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21731477056 + 24000201 = 147416^2 + 4899^2 .

It is a cyclic number.

It is not a de Polignac number, because 21755477257 - 2⁷ = 21755477129 is a prime.

It is not a weakly prime, because it can be changed into another prime (21755477357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10877738628 + 10877738629.

It is an arithmetic number, because the mean of its divisors is an integer number (10877738629).

Almost surely, 2^21755477257 is an apocalyptic number.

It is an amenable number.

21755477257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21755477257 is an equidigital number, since it uses as much as digits as its factorization.

21755477257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4802000, while the sum is 52.

The spelling of 21755477257 in words is "twenty-one billion, seven hundred fifty-five million, four hundred seventy-seven thousand, two hundred fifty-seven".