640001983 has 4 divisors (see below), whose sum is σ = 641056960. Its totient is φ = 638947008.

The previous prime is 640001927. The next prime is 640001993. The reversal of 640001983 is 389100046.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640001983 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 (640001903) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 526578 + ... + 527791.

It is an arithmetic number, because the mean of its divisors is an integer number (160264240).

Almost surely, 2^640001983 is an apocalyptic number.

640001983 is a deficient number, since it is larger than the sum of its proper divisors (1054977).

640001983 is a wasteful number, since it uses less digits than its factorization.

640001983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1054976.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 640001983 is about 25298.2604737954. The cubic root of 640001983 is about 861.7747660627.

The spelling of 640001983 in words is "six hundred forty million, one thousand, nine hundred eighty-three".