640243263 has 16 divisors (see below), whose sum is σ = 931919616. Its totient is φ = 387752640.

The previous prime is 640243213. The next prime is 640243291. The reversal of 640243263 is 362342046.

It is a happy number.

It is not a de Polignac number, because 640243263 - 2⁹ = 640242751 is a prime.

It is a super-2 number, since 2×640243263² = 819822871633774338, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 640243263.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640243213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46995 + ... + 59067.

It is an arithmetic number, because the mean of its divisors is an integer number (58244976).

Almost surely, 2^640243263 is an apocalyptic number.

640243263 is a deficient number, since it is larger than the sum of its proper divisors (291676353).

640243263 is a wasteful number, since it uses less digits than its factorization.

640243263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13694.

The product of its (nonzero) digits is 20736, while the sum is 30.

The square root of 640243263 is about 25303.0287317546. The cubic root of 640243263 is about 861.8830484831.

The spelling of 640243263 in words is "six hundred forty million, two hundred forty-three thousand, two hundred sixty-three".