691615680 has 224 divisors, whose sum is σ = 2536911360. Its totient is φ = 156364800.

The previous prime is 691615667. The next prime is 691615699. The reversal of 691615680 is 86516196.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (42).

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, 678211 + ... + 679229.

Almost surely, 2^691615680 is an apocalyptic number.

691615680 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 691615680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1268455680).

691615680 is an abundant number, since it is smaller than the sum of its proper divisors (1845295680).

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

691615680 is a wasteful number, since it uses less digits than its factorization.

691615680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1147 (or 1137 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 42.

The square root of 691615680 is about 26298.5870342876. The cubic root of 691615680 is about 884.3447670037.

The spelling of 691615680 in words is "six hundred ninety-one million, six hundred fifteen thousand, six hundred eighty".