21615369929 has 2 divisors, whose sum is σ = 21615369930. Its totient is φ = 21615369928.

The previous prime is 21615369913. The next prime is 21615369961. The reversal of 21615369929 is 92996351612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20829128329 + 786241600 = 144323^2 + 28040^2 .

It is a cyclic number.

It is not a de Polignac number, because 21615369929 - 2⁴ = 21615369913 is a prime.

It is not a weakly prime, because it can be changed into another prime (21615369029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10807684964 + 10807684965.

It is an arithmetic number, because the mean of its divisors is an integer number (10807684965).

Almost surely, 2^21615369929 is an apocalyptic number.

It is an amenable number.

21615369929 is a deficient number, since it is larger than the sum of its proper divisors (1).

21615369929 is an equidigital number, since it uses as much as digits as its factorization.

21615369929 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1574640, while the sum is 53.

The spelling of 21615369929 in words is "twenty-one billion, six hundred fifteen million, three hundred sixty-nine thousand, nine hundred twenty-nine".