640655253 has 36 divisors (see below), whose sum is σ = 1083045600. Its totient is φ = 363854736.

The previous prime is 640655231. The next prime is 640655263. The reversal of 640655253 is 352556046.

It is a happy number.

640655253 is a `hidden beast` number, since 640 + 6 + 5 + 5 + 2 + 5 + 3 = 666.

It is not a de Polignac number, because 640655253 - 2¹³ = 640647061 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640655263) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 69298 + ... + 77996.

It is an arithmetic number, because the mean of its divisors is an integer number (30084600).

Almost surely, 2^640655253 is an apocalyptic number.

640655253 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

It is an amenable number.

640655253 is a deficient number, since it is larger than the sum of its proper divisors (442390347).

640655253 is a wasteful number, since it uses less digits than its factorization.

640655253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8886 (or 8876 counting only the distinct ones).

The product of its (nonzero) digits is 108000, while the sum is 36.

The square root of 640655253 is about 25311.1685427599. The cubic root of 640655253 is about 862.0678798224.

The spelling of 640655253 in words is "six hundred forty million, six hundred fifty-five thousand, two hundred fifty-three".