691887864 has 128 divisors (see below), whose sum is σ = 1847292480. Its totient is φ = 215654400.

The previous prime is 691887857. The next prime is 691887899. The reversal of 691887864 is 468788196.

It is a congruent 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, 2870784 + ... + 2871024.

Almost surely, 2^691887864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691887864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (923646240).

691887864 is an abundant number, since it is smaller than the sum of its proper divisors (1155404616).

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

691887864 is a wasteful number, since it uses less digits than its factorization.

691887864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401 (or 397 counting only the distinct ones).

The product of its digits is 4644864, while the sum is 57.

The square root of 691887864 is about 26303.7614040274. The cubic root of 691887864 is about 884.4607625070.

The spelling of 691887864 in words is "six hundred ninety-one million, eight hundred eighty-seven thousand, eight hundred sixty-four".