631513978 has 4 divisors (see below), whose sum is σ = 947270970. Its totient is φ = 315756988.

The previous prime is 631513957. The next prime is 631514017. The reversal of 631513978 is 879315136.

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., 606981769 + 24532209 = 24637^2 + 4953^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 157878493 + ... + 157878496.

Almost surely, 2^631513978 is an apocalyptic number.

631513978 is a deficient number, since it is larger than the sum of its proper divisors (315756992).

631513978 is a wasteful number, since it uses less digits than its factorization.

631513978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 315756991.

The product of its digits is 136080, while the sum is 43.

The square root of 631513978 is about 25129.9418622487. The cubic root of 631513978 is about 857.9480455679.

The spelling of 631513978 in words is "six hundred thirty-one million, five hundred thirteen thousand, nine hundred seventy-eight".