15721515137 has 2 divisors, whose sum is σ = 15721515138. Its totient is φ = 15721515136.

The previous prime is 15721515109. The next prime is 15721515157. The reversal of 15721515137 is 73151512751.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12639155776 + 3082359361 = 112424^2 + 55519^2 .

It is a cyclic number.

It is not a de Polignac number, because 15721515137 - 2²² = 15717320833 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 15721515137.

It is not a weakly prime, because it can be changed into another prime (15721515157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7860757568 + 7860757569.

It is an arithmetic number, because the mean of its divisors is an integer number (7860757569).

Almost surely, 2^15721515137 is an apocalyptic number.

It is an amenable number.

15721515137 is a deficient number, since it is larger than the sum of its proper divisors (1).

15721515137 is an equidigital number, since it uses as much as digits as its factorization.

15721515137 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36750, while the sum is 38.

The spelling of 15721515137 in words is "fifteen billion, seven hundred twenty-one million, five hundred fifteen thousand, one hundred thirty-seven".