31021712521 has 2 divisors, whose sum is σ = 31021712522. Its totient is φ = 31021712520.

The previous prime is 31021712497. The next prime is 31021712587. The reversal of 31021712521 is 12521712013.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22601814921 + 8419897600 = 150339^2 + 91760^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31021712521 is a prime.

It is a super-4 number, since 4×31021712521⁴ (a number of 43 digits) contains 4444 as substring.

It is not a weakly prime, because it can be changed into another prime (31021712221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15510856260 + 15510856261.

It is an arithmetic number, because the mean of its divisors is an integer number (15510856261).

Almost surely, 2^31021712521 is an apocalyptic number.

It is an amenable number.

31021712521 is a deficient number, since it is larger than the sum of its proper divisors (1).

31021712521 is an equidigital number, since it uses as much as digits as its factorization.

31021712521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 25.

The spelling of 31021712521 in words is "thirty-one billion, twenty-one million, seven hundred twelve thousand, five hundred twenty-one".