646997724 has 72 divisors (see below), whose sum is σ = 1666435680. Its totient is φ = 211612800.

The previous prime is 646997711. The next prime is 646997749. The reversal of 646997724 is 427799646.

It is a happy number.

It is a super-2 number, since 2×646997724² = 837212109722360352, which contains 22 as substring.

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, 687094 + ... + 688034.

It is an arithmetic number, because the mean of its divisors is an integer number (23144940).

Almost surely, 2^646997724 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 646997724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (833217840).

646997724 is an abundant number, since it is smaller than the sum of its proper divisors (1019437956).

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

646997724 is a wasteful number, since it uses less digits than its factorization.

646997724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1291 (or 1286 counting only the distinct ones).

The product of its digits is 4572288, while the sum is 54.

The square root of 646997724 is about 25436.1499445179. The cubic root of 646997724 is about 864.9033600702.

The spelling of 646997724 in words is "six hundred forty-six million, nine hundred ninety-seven thousand, seven hundred twenty-four".