688917977 has 18 divisors (see below), whose sum is σ = 765412074. Its totient is φ = 619597440.

The previous prime is 688917953. The next prime is 688917989. The reversal of 688917977 is 779719886.

It can be written as a sum of positive squares in only one way, i.e., 564015001 + 124902976 = 23749^2 + 11176^2 .

It is not a de Polignac number, because 688917977 - 2¹² = 688913881 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688910977) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1951433 + ... + 1951785.

It is an arithmetic number, because the mean of its divisors is an integer number (42522893).

Almost surely, 2^688917977 is an apocalyptic number.

It is an amenable number.

688917977 is a deficient number, since it is larger than the sum of its proper divisors (76494097).

688917977 is a wasteful number, since it uses less digits than its factorization.

688917977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 629 (or 491 counting only the distinct ones).

The product of its digits is 10668672, while the sum is 62.

The square root of 688917977 is about 26247.2470365941. The cubic root of 688917977 is about 883.1934492942.

The spelling of 688917977 in words is "six hundred eighty-eight million, nine hundred seventeen thousand, nine hundred seventy-seven".