691385052870 has 512 divisors, whose sum is σ = 2051868672000. Its totient is φ = 165105008640.

The previous prime is 691385052851. The next prime is 691385052913. The reversal of 691385052870 is 78250583196.

691385052870 is a `hidden beast` number, since 69 + 1 + 3 + 8 + 50 + 528 + 7 + 0 = 666.

691385052870 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 744224566 + ... + 744225494.

It is an arithmetic number, because the mean of its divisors is an integer number (4007556000).

Almost surely, 2^691385052870 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691385052870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1025934336000).

691385052870 is an abundant number, since it is smaller than the sum of its proper divisors (1360483619130).

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

691385052870 is a wasteful number, since it uses less digits than its factorization.

691385052870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1125 (or 1119 counting only the distinct ones).

The product of its (nonzero) digits is 3628800, while the sum is 54.

The spelling of 691385052870 in words is "six hundred ninety-one billion, three hundred eighty-five million, fifty-two thousand, eight hundred seventy".