688642564 has 9 divisors (see below), whose sum is σ = 1205216341. Its totient is φ = 344295040.

The previous prime is 688642547. The next prime is 688642567. The reversal of 688642564 is 465246886.

The square root of 688642564 is 26242.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 97180164 + 591462400 = 9858^2 + 24320^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (688642567) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 45924 + ... + 59044.

Almost surely, 2^688642564 is an apocalyptic number.

688642564 is the 26242-nd square number.

It is an amenable number.

688642564 is a deficient number, since it is larger than the sum of its proper divisors (516573777).

688642564 is an frugal number, since it uses more digits than its factorization.

688642564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26246 (or 13123 counting only the distinct ones).

The product of its digits is 2211840, while the sum is 49.

The cubic root of 688642564 is about 883.0757403714.

Multiplying 688642564 by its sum of digits (49), we get a square (33743485636 = 183694²).

The spelling of 688642564 in words is "six hundred eighty-eight million, six hundred forty-two thousand, five hundred sixty-four".