688137978 has 32 divisors (see below), whose sum is σ = 1503322560. Its totient is φ = 208258560.

The previous prime is 688137971. The next prime is 688137979. The reversal of 688137978 is 879731886.

It is not an unprimeable number, because it can be changed into a prime (688137971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48426 + ... + 61002.

It is an arithmetic number, because the mean of its divisors is an integer number (46978830).

Almost surely, 2^688137978 is an apocalyptic number.

688137978 is an abundant number, since it is smaller than the sum of its proper divisors (815184582).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

688137978 is a wasteful number, since it uses less digits than its factorization.

688137978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13422.

The product of its digits is 4064256, while the sum is 57.

The square root of 688137978 is about 26232.3841463181. The cubic root of 688137978 is about 882.8600036190.

The spelling of 688137978 in words is "six hundred eighty-eight million, one hundred thirty-seven thousand, nine hundred seventy-eight".