640426900 has 18 divisors (see below), whose sum is σ = 1389726590. Its totient is φ = 256170720.

The previous prime is 640426877. The next prime is 640426909. The reversal of 640426900 is 9624046.

It can be written as a sum of positive squares in 3 ways, for example, as 1449616 + 638977284 = 1204^2 + 25278^2 .

It is a super-2 number, since 2×640426900² = 820293228487220000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640426909) 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, 3202035 + ... + 3202234.

Almost surely, 2^640426900 is an apocalyptic number.

It is an amenable number.

640426900 is an abundant number, since it is smaller than the sum of its proper divisors (749299690).

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

640426900 is a wasteful number, since it uses less digits than its factorization.

640426900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6404283 (or 6404276 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 640426900 is about 25306.6572269038. The cubic root of 640426900 is about 861.9654434605.

The spelling of 640426900 in words is "six hundred forty million, four hundred twenty-six thousand, nine hundred".