691568640 has 384 divisors, whose sum is σ = 2780781120. Its totient is φ = 155713536.

The previous prime is 691568609. The next prime is 691568663. The reversal of 691568640 is 46865196.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10321887 + ... + 10321953.

Almost surely, 2^691568640 is an apocalyptic number.

691568640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691568640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1390390560).

691568640 is an abundant number, since it is smaller than the sum of its proper divisors (2089212480).

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

691568640 is an equidigital number, since it uses as much as digits as its factorization.

691568640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The square root of 691568640 is about 26297.6926744534. The cubic root of 691568640 is about 884.3247170819.

The spelling of 691568640 in words is "six hundred ninety-one million, five hundred sixty-eight thousand, six hundred forty".