645636 has 24 divisors (see below), whose sum is σ = 1520064. Its totient is φ = 213280.

The previous prime is 645629. The next prime is 645641. The reversal of 645636 is 636546.

It is an unprimeable number.

645636 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1921 + ... + 2231.

It is an arithmetic number, because the mean of its divisors is an integer number (63336).

2⁶⁴⁵⁶³⁶ is an apocalyptic number.

It is an amenable number.

645636 is an abundant number, since it is smaller than the sum of its proper divisors (874428).

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

645636 is a wasteful number, since it uses less digits than its factorization.

645636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491 (or 489 counting only the distinct ones).

The product of its digits is 12960, while the sum is 30.

The square root of 645636 is about 803.5147789556. The cubic root of 645636 is about 86.4296151906.

The spelling of 645636 in words is "six hundred forty-five thousand, six hundred thirty-six".