688611640 has 32 divisors (see below), whose sum is σ = 1557180000. Its totient is φ = 274057344.

The previous prime is 688611631. The next prime is 688611643. The reversal of 688611640 is 46116886.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 688611593 and 688611602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688611643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35295 + ... + 51214.

It is an arithmetic number, because the mean of its divisors is an integer number (48661875).

Almost surely, 2^688611640 is an apocalyptic number.

It is an amenable number.

688611640 is an abundant number, since it is smaller than the sum of its proper divisors (868568360).

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

688611640 is a wasteful number, since it uses less digits than its factorization.

688611640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86719 (or 86715 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 40.

The square root of 688611640 is about 26241.4107852455. The cubic root of 688611640 is about 883.0625217853.

The spelling of 688611640 in words is "six hundred eighty-eight million, six hundred eleven thousand, six hundred forty".