687631978 has 32 divisors (see below), whose sum is σ = 1142372160. Its totient is φ = 307824000.

The previous prime is 687631957. The next prime is 687631979. The reversal of 687631978 is 879136786.

It is not an unprimeable number, because it can be changed into a prime (687631979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 647568 + ... + 648628.

It is an arithmetic number, because the mean of its divisors is an integer number (35699130).

Almost surely, 2^687631978 is an apocalyptic number.

687631978 is a deficient number, since it is larger than the sum of its proper divisors (454740182).

687631978 is a wasteful number, since it uses less digits than its factorization.

687631978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1494.

The product of its digits is 3048192, while the sum is 55.

The square root of 687631978 is about 26222.7378051949. The cubic root of 687631978 is about 882.6435563771.

The spelling of 687631978 in words is "six hundred eighty-seven million, six hundred thirty-one thousand, nine hundred seventy-eight".