661813983 has 40 divisors (see below), whose sum is σ = 1039550688. Its totient is φ = 418784256.

The previous prime is 661813963. The next prime is 661814039. The reversal of 661813983 is 389318166.

It is a happy number.

It is not a de Polignac number, because 661813983 - 2⁵ = 661813951 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661813963) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 253935 + ... + 256527.

Almost surely, 2^661813983 is an apocalyptic number.

661813983 is a deficient number, since it is larger than the sum of its proper divisors (377736705).

661813983 is a wasteful number, since it uses less digits than its factorization.

661813983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2765 (or 2756 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 661813983 is about 25725.7455285556. The cubic root of 661813983 is about 871.4556961253.

The spelling of 661813983 in words is "six hundred sixty-one million, eight hundred thirteen thousand, nine hundred eighty-three".