645453900 has 576 divisors, whose sum is σ = 2659829760. Its totient is φ = 130636800.

The previous prime is 645453881. The next prime is 645453901. The reversal of 645453900 is 9354546.

It is a happy number.

645453900 is a `hidden beast` number, since 645 + 4 + 5 + 3 + 9 + 0 + 0 = 666.

It is a super-2 number, since 2×645453900² = 833221474050420000, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (645453901) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 9090865 + ... + 9090935.

It is an arithmetic number, because the mean of its divisors is an integer number (4617760).

Almost surely, 2^645453900 is an apocalyptic number.

645453900 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 645453900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1329914880).

645453900 is an abundant number, since it is smaller than the sum of its proper divisors (2014375860).

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

645453900 is a wasteful number, since it uses less digits than its factorization.

645453900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The square root of 645453900 is about 25405.7847743383. The cubic root of 645453900 is about 864.2148867514.

The spelling of 645453900 in words is "six hundred forty-five million, four hundred fifty-three thousand, nine hundred".