661995983 has 8 divisors (see below), whose sum is σ = 725921616. Its totient is φ = 598694400.

The previous prime is 661995949. The next prime is 661995991. The reversal of 661995983 is 389599166.

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 661995983 - 2⁸ = 661995727 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 (661995583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 153788 + ... + 158033.

It is an arithmetic number, because the mean of its divisors is an integer number (90740202).

Almost surely, 2^661995983 is an apocalyptic number.

661995983 is a deficient number, since it is larger than the sum of its proper divisors (63925633).

661995983 is a wasteful number, since it uses less digits than its factorization.

661995983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312025.

The product of its digits is 3149280, while the sum is 56.

The square root of 661995983 is about 25729.2825978495. The cubic root of 661995983 is about 871.5355727493.

The spelling of 661995983 in words is "six hundred sixty-one million, nine hundred ninety-five thousand, nine hundred eighty-three".