640254263 has 4 divisors (see below), whose sum is σ = 698459208. Its totient is φ = 582049320.

The previous prime is 640254239. The next prime is 640254269. The reversal of 640254263 is 362452046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640254263 - 2¹⁰ = 640253239 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640254269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29102456 + ... + 29102477.

It is an arithmetic number, because the mean of its divisors is an integer number (174614802).

Almost surely, 2^640254263 is an apocalyptic number.

640254263 is a deficient number, since it is larger than the sum of its proper divisors (58204945).

640254263 is a wasteful number, since it uses less digits than its factorization.

640254263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58204944.

The product of its (nonzero) digits is 34560, while the sum is 32.

The square root of 640254263 is about 25303.2460961040. The cubic root of 640254263 is about 861.8879844503.

The spelling of 640254263 in words is "six hundred forty million, two hundred fifty-four thousand, two hundred sixty-three".