21427969697 has 2 divisors, whose sum is σ = 21427969698. Its totient is φ = 21427969696.

The previous prime is 21427969669. The next prime is 21427969721. The reversal of 21427969697 is 79696972412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18368109841 + 3059859856 = 135529^2 + 55316^2 .

It is a cyclic number.

It is not a de Polignac number, because 21427969697 - 2²² = 21423775393 is a prime.

It is not a weakly prime, because it can be changed into another prime (21427968697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10713984848 + 10713984849.

It is an arithmetic number, because the mean of its divisors is an integer number (10713984849).

Almost surely, 2^21427969697 is an apocalyptic number.

It is an amenable number.

21427969697 is a deficient number, since it is larger than the sum of its proper divisors (1).

21427969697 is an equidigital number, since it uses as much as digits as its factorization.

21427969697 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20575296, while the sum is 62.

The spelling of 21427969697 in words is "twenty-one billion, four hundred twenty-seven million, nine hundred sixty-nine thousand, six hundred ninety-seven".