21697053737 has 2 divisors, whose sum is σ = 21697053738. Its totient is φ = 21697053736.

The previous prime is 21697053733. The next prime is 21697053757. The reversal of 21697053737 is 73735079612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20981812201 + 715241536 = 144851^2 + 26744^2 .

It is a cyclic number.

It is not a de Polignac number, because 21697053737 - 2² = 21697053733 is a prime.

It is not a weakly prime, because it can be changed into another prime (21697053733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10848526868 + 10848526869.

It is an arithmetic number, because the mean of its divisors is an integer number (10848526869).

Almost surely, 2^21697053737 is an apocalyptic number.

It is an amenable number.

21697053737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21697053737 is an equidigital number, since it uses as much as digits as its factorization.

21697053737 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1666980, while the sum is 50.

The spelling of 21697053737 in words is "twenty-one billion, six hundred ninety-seven million, fifty-three thousand, seven hundred thirty-seven".