31521667129 has 2 divisors, whose sum is σ = 31521667130. Its totient is φ = 31521667128.

The previous prime is 31521667061. The next prime is 31521667139. The reversal of 31521667129 is 92176612513.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 22431951529 + 9089715600 = 149773^2 + 95340^2 .

It is an emirp because it is prime and its reverse (92176612513) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31521667129 - 2²⁵ = 31488112697 is a prime.

It is not a weakly prime, because it can be changed into another prime (31521667139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15760833564 + 15760833565.

It is an arithmetic number, because the mean of its divisors is an integer number (15760833565).

Almost surely, 2^31521667129 is an apocalyptic number.

It is an amenable number.

31521667129 is a deficient number, since it is larger than the sum of its proper divisors (1).

31521667129 is an equidigital number, since it uses as much as digits as its factorization.

31521667129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 43.

The spelling of 31521667129 in words is "thirty-one billion, five hundred twenty-one million, six hundred sixty-seven thousand, one hundred twenty-nine".