645980736 has 56 divisors (see below), whose sum is σ = 1719726304. Its totient is φ = 213995520.

The previous prime is 645980729. The next prime is 645980747. The reversal of 645980736 is 637089546.

It is a super-2 number, since 2×645980736² = 834582222566203392, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20976 + ... + 41616.

Almost surely, 2^645980736 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 645980736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (859863152).

645980736 is an abundant number, since it is smaller than the sum of its proper divisors (1073745568).

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

645980736 is a wasteful number, since it uses less digits than its factorization.

645980736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20819 (or 20809 counting only the distinct ones).

The product of its (nonzero) digits is 1088640, while the sum is 48.

The square root of 645980736 is about 25416.1510854811. The cubic root of 645980736 is about 864.4499542465.

The spelling of 645980736 in words is "six hundred forty-five million, nine hundred eighty thousand, seven hundred thirty-six".