645642 has 12 divisors (see below), whose sum is σ = 1398930. Its totient is φ = 215208.

The previous prime is 645641. The next prime is 645647. The reversal of 645642 is 246546.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 423801 + 221841 = 651^2 + 471^2 .

It is not an unprimeable number, because it can be changed into a prime (645641) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17917 + ... + 17952.

2⁶⁴⁵⁶⁴² is an apocalyptic number.

645642 is an abundant number, since it is smaller than the sum of its proper divisors (753288).

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

645642 is a wasteful number, since it uses less digits than its factorization.

645642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35877 (or 35874 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 645642 is about 803.5185125434. The cubic root of 645642 is about 86.4298829246.

The spelling of 645642 in words is "six hundred forty-five thousand, six hundred forty-two".