645632 has 40 divisors (see below), whose sum is σ = 1403556. Its totient is φ = 294912.

The previous prime is 645629. The next prime is 645641. The reversal of 645632 is 236546.

It can be written as a sum of positive squares in 2 ways, for example, as 614656 + 30976 = 784^2 + 176^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6608 + ... + 6704.

2⁶⁴⁵⁶³² 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 645632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (701778).

645632 is an abundant number, since it is smaller than the sum of its proper divisors (757924).

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

645632 is an equidigital number, since it uses as much as digits as its factorization.

645632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128 (or 112 counting only the distinct ones).

The product of its digits is 4320, while the sum is 26.

The square root of 645632 is about 803.5122898873. The cubic root of 645632 is about 86.4294367004.

The spelling of 645632 in words is "six hundred forty-five thousand, six hundred thirty-two".