21137809057 has 2 divisors, whose sum is σ = 21137809058. Its totient is φ = 21137809056.

The previous prime is 21137809039. The next prime is 21137809081. The reversal of 21137809057 is 75090873112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14993757601 + 6144051456 = 122449^2 + 78384^2 .

It is a cyclic number.

It is not a de Polignac number, because 21137809057 - 2⁷ = 21137808929 is a prime.

It is a super-3 number, since 3×21137809057³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21137806057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10568904528 + 10568904529.

It is an arithmetic number, because the mean of its divisors is an integer number (10568904529).

Almost surely, 2^21137809057 is an apocalyptic number.

It is an amenable number.

21137809057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21137809057 is an equidigital number, since it uses as much as digits as its factorization.

21137809057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 105840, while the sum is 43.

The spelling of 21137809057 in words is "twenty-one billion, one hundred thirty-seven million, eight hundred nine thousand, fifty-seven".