691638012 has 72 divisors (see below), whose sum is σ = 1886692080. Its totient is φ = 212371200.

The previous prime is 691637987. The next prime is 691638043. The reversal of 691638012 is 210836196.

691638012 is a `hidden beast` number, since 6 + 9 + 1 + 638 + 0 + 12 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 280039 + ... + 282497.

Almost surely, 2^691638012 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 691638012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (943346040).

691638012 is an abundant number, since it is smaller than the sum of its proper divisors (1195054068).

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

691638012 is a wasteful number, since it uses less digits than its factorization.

691638012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3083 (or 3078 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 691638012 is about 26299.0116164087. The cubic root of 691638012 is about 884.3542852836.

The spelling of 691638012 in words is "six hundred ninety-one million, six hundred thirty-eight thousand, twelve".