691356988 has 24 divisors (see below), whose sum is σ = 1420086752. Its totient is φ = 288287424.

The previous prime is 691356983. The next prime is 691357021. The reversal of 691356988 is 889653196.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691356983) 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, 332631 + ... + 334702.

Almost surely, 2^691356988 is an apocalyptic number.

It is an amenable number.

691356988 is an abundant number, since it is smaller than the sum of its proper divisors (728729764).

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

691356988 is a wasteful number, since it uses less digits than its factorization.

691356988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 667381 (or 667379 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 55.

The square root of 691356988 is about 26293.6682111873. The cubic root of 691356988 is about 884.2344931178.

The spelling of 691356988 in words is "six hundred ninety-one million, three hundred fifty-six thousand, nine hundred eighty-eight".