640533632 has 24 divisors (see below), whose sum is σ = 1276633785. Its totient is φ = 320123648.

The previous prime is 640533631. The next prime is 640533661. The reversal of 640533632 is 236335046.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 578691136 + 61842496 = 24056^2 + 7864^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=17896.

It is a super-2 number, since 2×640533632² = 820566667446222848, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640533631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 285218 + ... + 287454.

Almost surely, 2^640533632 is an apocalyptic number.

It is an amenable number.

640533632 is a deficient number, since it is larger than the sum of its proper divisors (636100153).

640533632 is an frugal number, since it uses more digits than its factorization.

640533632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4488 (or 2239 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 32.

The square root of 640533632 is about 25308.7659122289. The cubic root of 640533632 is about 862.0133251601.

Multiplying 640533632 by its sum of digits (32), we get a square (20497076224 = 143168²).

640533632 divided by its sum of digits (32) gives a square (20016676 = 4474²).

Adding to 640533632 its reverse (236335046), we get a palindrome (876868678).

The spelling of 640533632 in words is "six hundred forty million, five hundred thirty-three thousand, six hundred thirty-two".