391021640464 has 80 divisors (see below), whose sum is σ = 935619616512. Its totient is φ = 154161759744.

The previous prime is 391021640417. The next prime is 391021640497. The reversal of 391021640464 is 464046120193.

It is a super-2 number, since 2×391021640464² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31684 + ... + 884899.

Almost surely, 2^391021640464 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 391021640464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (467809808256).

391021640464 is an abundant number, since it is smaller than the sum of its proper divisors (544597976048).

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

391021640464 is a wasteful number, since it uses less digits than its factorization.

391021640464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 916904 (or 916898 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 40.

The spelling of 391021640464 in words is "three hundred ninety-one billion, twenty-one million, six hundred forty thousand, four hundred sixty-four".