31215401981 has 16 divisors (see below), whose sum is σ = 33113041920. Its totient is φ = 29374410240.

The previous prime is 31215401977. The next prime is 31215402007. The reversal of 31215401981 is 18910451213.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 31215401981 - 2² = 31215401977 is a prime.

It is a super-2 number, since 2×31215401981² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31215401081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2159480 + ... + 2173886.

It is an arithmetic number, because the mean of its divisors is an integer number (2069565120).

Almost surely, 2^31215401981 is an apocalyptic number.

31215401981 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

31215401981 is a deficient number, since it is larger than the sum of its proper divisors (1897639939).

31215401981 is a wasteful number, since it uses less digits than its factorization.

31215401981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16364.

The product of its (nonzero) digits is 8640, while the sum is 35.

The spelling of 31215401981 in words is "thirty-one billion, two hundred fifteen million, four hundred one thousand, nine hundred eighty-one".