856665646740 has 72 divisors (see below), whose sum is σ = 2622392452680. Its totient is φ = 226348349184.

The previous prime is 856665646729. The next prime is 856665646763. The reversal of 856665646740 is 47646566658.

It can be written as a sum of positive squares in 4 ways, for example, as 297212509584 + 559453137156 = 545172^2 + 747966^2 .

It is a hoax number, since the sum of its digits (63) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21811819 + ... + 21851058.

Almost surely, 2^856665646740 is an apocalyptic number.

It is an amenable number.

856665646740 is an abundant number, since it is smaller than the sum of its proper divisors (1765726805940).

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

856665646740 is a wasteful number, since it uses less digits than its factorization.

856665646740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43663001 (or 43662996 counting only the distinct ones).

The product of its (nonzero) digits is 174182400, while the sum is 63.

The spelling of 856665646740 in words is "eight hundred fifty-six billion, six hundred sixty-five million, six hundred forty-six thousand, seven hundred forty".