640123983 has 24 divisors (see below), whose sum is σ = 947963952. Its totient is φ = 416078208.

The previous prime is 640123949. The next prime is 640123987. The reversal of 640123983 is 389321046.

640123983 is a `hidden beast` number, since 640 + 1 + 2 + 3 + 9 + 8 + 3 = 666.

It is not a de Polignac number, because 640123983 - 2¹⁸ = 639861839 is a prime.

It is a super-2 number, since 2×640123983² = 819517427223568578, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640123987) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 73635 + ... + 81867.

It is an arithmetic number, because the mean of its divisors is an integer number (39498498).

Almost surely, 2^640123983 is an apocalyptic number.

640123983 is a deficient number, since it is larger than the sum of its proper divisors (307839969).

640123983 is a wasteful number, since it uses less digits than its factorization.

640123983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8455 (or 8452 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 640123983 is about 25300.6715918768. The cubic root of 640123983 is about 861.8295210189.

The spelling of 640123983 in words is "six hundred forty million, one hundred twenty-three thousand, nine hundred eighty-three".