688745538 has 64 divisors (see below), whose sum is σ = 1701504000. Its totient is φ = 205079040.

The previous prime is 688745521. The next prime is 688745543. The reversal of 688745538 is 835547886.

688745538 is a `hidden beast` number, since 6 + 8 + 87 + 4 + 553 + 8 = 666.

It is a super-2 number, since 2×688745538² = 948740832229818888, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5938 + ... + 37586.

It is an arithmetic number, because the mean of its divisors is an integer number (26586000).

Almost surely, 2^688745538 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 688745538, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (850752000).

688745538 is an abundant number, since it is smaller than the sum of its proper divisors (1012758462).

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

688745538 is a wasteful number, since it uses less digits than its factorization.

688745538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31704 (or 31698 counting only the distinct ones).

The product of its digits is 6451200, while the sum is 54.

The square root of 688745538 is about 26243.9619341288. The cubic root of 688745538 is about 883.1197541622.

It can be divided in two parts, 6887 and 45538, that added together give a palindrome (52425).

The spelling of 688745538 in words is "six hundred eighty-eight million, seven hundred forty-five thousand, five hundred thirty-eight".