691505856 has 224 divisors, whose sum is σ = 2153594880. Its totient is φ = 217147392.

The previous prime is 691505851. The next prime is 691505887. The reversal of 691505856 is 658505196.

It is a happy number.

691505856 is a `hidden beast` number, since 6 + 91 + 505 + 8 + 56 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691505851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5047420 + ... + 5047556.

Almost surely, 2^691505856 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 691505856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1076797440).

691505856 is an abundant number, since it is smaller than the sum of its proper divisors (1462089024).

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

691505856 is a wasteful number, since it uses less digits than its factorization.

691505856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308 (or 292 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 45.

The square root of 691505856 is about 26296.4989304660. The cubic root of 691505856 is about 884.2979551573.

The spelling of 691505856 in words is "six hundred ninety-one million, five hundred five thousand, eight hundred fifty-six".