645765120 has 864 divisors, whose sum is σ = 3058670160. Its totient is φ = 123863040.

The previous prime is 645765073. The next prime is 645765121. The reversal of 645765120 is 21567546.

It is a happy number.

645765120 is a `hidden beast` number, since 64 + 576 + 5 + 1 + 20 = 666.

It is a super-2 number, since 2×645765120² = 834025180417228800, which contains 22 as substring.

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 (645765121) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 49674234 + ... + 49674246.

Almost surely, 2^645765120 is an apocalyptic number.

645765120 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645765120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1529335080).

645765120 is an abundant number, since it is smaller than the sum of its proper divisors (2412905040).

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

645765120 is a wasteful number, since it uses less digits than its factorization.

645765120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71 (or 41 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 36.

The square root of 645765120 is about 25411.9090191981. The cubic root of 645765120 is about 864.3537645964.

It can be divided in two parts, 64576 and 5120, that added together give a palindrome (69696).

The spelling of 645765120 in words is "six hundred forty-five million, seven hundred sixty-five thousand, one hundred twenty".