645117372 has 72 divisors (see below), whose sum is σ = 1706905200. Its totient is φ = 213031296.

The previous prime is 645117367. The next prime is 645117373. The reversal of 645117372 is 273711546.

It is a happy number.

645117372 is a `hidden beast` number, since 6 + 4 + 511 + 73 + 72 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645117373) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 102904 + ... + 108992.

Almost surely, 2^645117372 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 645117372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (853452600).

645117372 is an abundant number, since it is smaller than the sum of its proper divisors (1061787828).

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

645117372 is a wasteful number, since it uses less digits than its factorization.

645117372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6217 (or 6203 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 645117372 is about 25399.1608522801. The cubic root of 645117372 is about 864.0646652990.

The spelling of 645117372 in words is "six hundred forty-five million, one hundred seventeen thousand, three hundred seventy-two".