640611983 has 8 divisors (see below), whose sum is σ = 699224016. Its totient is φ = 582062400.

The previous prime is 640611971. The next prime is 640612009. The reversal of 640611983 is 389116046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640611983 - 2⁶ = 640611919 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 (640611953) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7313 + ... + 36533.

It is an arithmetic number, because the mean of its divisors is an integer number (87403002).

Almost surely, 2^640611983 is an apocalyptic number.

640611983 is a deficient number, since it is larger than the sum of its proper divisors (58612033).

640611983 is a wasteful number, since it uses less digits than its factorization.

640611983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31225.

The product of its (nonzero) digits is 31104, while the sum is 38.

The square root of 640611983 is about 25310.3137673163. The cubic root of 640611983 is about 862.0484712992.

The spelling of 640611983 in words is "six hundred forty million, six hundred eleven thousand, nine hundred eighty-three".