31213301981 has 2 divisors, whose sum is σ = 31213301982. Its totient is φ = 31213301980.

The previous prime is 31213301891. The next prime is 31213301983. The reversal of 31213301981 is 18910331213.

Together with previous prime (31213301891) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16463199481 + 14750102500 = 128309^2 + 121450^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31213301981 is a prime.

It is a super-2 number, since 2×31213301981² (a number of 22 digits) contains 22 as substring.

Together with 31213301983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31213301983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15606650990 + 15606650991.

It is an arithmetic number, because the mean of its divisors is an integer number (15606650991).

Almost surely, 2^31213301981 is an apocalyptic number.

It is an amenable number.

31213301981 is a deficient number, since it is larger than the sum of its proper divisors (1).

31213301981 is an equidigital number, since it uses as much as digits as its factorization.

31213301981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 32.

The spelling of 31213301981 in words is "thirty-one billion, two hundred thirteen million, three hundred one thousand, nine hundred eighty-one".