31615242521 has 2 divisors, whose sum is σ = 31615242522. Its totient is φ = 31615242520.

The previous prime is 31615242493. The next prime is 31615242559. The reversal of 31615242521 is 12524251613.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31493471296 + 121771225 = 177464^2 + 11035^2 .

It is an emirp because it is prime and its reverse (12524251613) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31615242521 is a prime.

It is not a weakly prime, because it can be changed into another prime (31615242221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15807621260 + 15807621261.

It is an arithmetic number, because the mean of its divisors is an integer number (15807621261).

Almost surely, 2^31615242521 is an apocalyptic number.

It is an amenable number.

31615242521 is a deficient number, since it is larger than the sum of its proper divisors (1).

31615242521 is an equidigital number, since it uses as much as digits as its factorization.

31615242521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14400, while the sum is 32.

The spelling of 31615242521 in words is "thirty-one billion, six hundred fifteen million, two hundred forty-two thousand, five hundred twenty-one".