31402990978 has 4 divisors (see below), whose sum is σ = 47104486470. Its totient is φ = 15701495488.

The previous prime is 31402990973. The next prime is 31402991017. The reversal of 31402990978 is 87909920413.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 30778140969 + 624850009 = 175437^2 + 24997^2 .

It is a super-2 number, since 2×31402990978² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (31402990973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7850747743 + ... + 7850747746.

Almost surely, 2^31402990978 is an apocalyptic number.

31402990978 is a deficient number, since it is larger than the sum of its proper divisors (15701495492).

31402990978 is a wasteful number, since it uses less digits than its factorization.

31402990978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15701495491.

The product of its (nonzero) digits is 979776, while the sum is 52.

The spelling of 31402990978 in words is "thirty-one billion, four hundred two million, nine hundred ninety thousand, nine hundred seventy-eight".