31421078721 has 6 divisors (see below), whose sum is σ = 45386002610. Its totient is φ = 20947385808.

The previous prime is 31421078713. The next prime is 31421078747. The reversal of 31421078721 is 12787012413.

It can be written as a sum of positive squares in only one way, i.e., 31116960000 + 304118721 = 176400^2 + 17439^2 .

It is not a de Polignac number, because 31421078721 - 2³ = 31421078713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31421078621) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1745615476 + ... + 1745615493.

Almost surely, 2^31421078721 is an apocalyptic number.

It is an amenable number.

31421078721 is a deficient number, since it is larger than the sum of its proper divisors (13964923889).

31421078721 is a wasteful number, since it uses less digits than its factorization.

31421078721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3491230975 (or 3491230972 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The spelling of 31421078721 in words is "thirty-one billion, four hundred twenty-one million, seventy-eight thousand, seven hundred twenty-one".