31512213521 has 2 divisors, whose sum is σ = 31512213522. Its totient is φ = 31512213520.

The previous prime is 31512213449. The next prime is 31512213533. The reversal of 31512213521 is 12531221513.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27350544400 + 4161669121 = 165380^2 + 64511^2 .

It is a cyclic number.

It is not a de Polignac number, because 31512213521 - 2¹⁰ = 31512212497 is a prime.

It is not a weakly prime, because it can be changed into another prime (31512213121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15756106760 + 15756106761.

It is an arithmetic number, because the mean of its divisors is an integer number (15756106761).

Almost surely, 2^31512213521 is an apocalyptic number.

It is an amenable number.

31512213521 is a deficient number, since it is larger than the sum of its proper divisors (1).

31512213521 is an equidigital number, since it uses as much as digits as its factorization.

31512213521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1800, while the sum is 26.

The spelling of 31512213521 in words is "thirty-one billion, five hundred twelve million, two hundred thirteen thousand, five hundred twenty-one".