21711637897 has 2 divisors, whose sum is σ = 21711637898. Its totient is φ = 21711637896.

The previous prime is 21711637891. The next prime is 21711637919. The reversal of 21711637897 is 79873611712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18538456336 + 3173181561 = 136156^2 + 56331^2 .

It is a cyclic number.

It is not a de Polignac number, because 21711637897 - 2³ = 21711637889 is a prime.

It is not a weakly prime, because it can be changed into another prime (21711637891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10855818948 + 10855818949.

It is an arithmetic number, because the mean of its divisors is an integer number (10855818949).

Almost surely, 2^21711637897 is an apocalyptic number.

It is an amenable number.

21711637897 is a deficient number, since it is larger than the sum of its proper divisors (1).

21711637897 is an equidigital number, since it uses as much as digits as its factorization.

21711637897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 889056, while the sum is 52.

The spelling of 21711637897 in words is "twenty-one billion, seven hundred eleven million, six hundred thirty-seven thousand, eight hundred ninety-seven".