661973885 has 4 divisors (see below), whose sum is σ = 794368668. Its totient is φ = 529579104.

The previous prime is 661973867. The next prime is 661973903. The reversal of 661973885 is 588379166.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (661973867) and next prime (661973903).

It can be written as a sum of positive squares in 2 ways, for example, as 376127236 + 285846649 = 19394^2 + 16907^2 .

It is a cyclic number.

It is not a de Polignac number, because 661973885 - 2⁶ = 661973821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66197384 + ... + 66197393.

It is an arithmetic number, because the mean of its divisors is an integer number (198592167).

Almost surely, 2^661973885 is an apocalyptic number.

It is an amenable number.

661973885 is a deficient number, since it is larger than the sum of its proper divisors (132394783).

661973885 is a wasteful number, since it uses less digits than its factorization.

661973885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132394782.

The product of its digits is 2177280, while the sum is 53.

The square root of 661973885 is about 25728.8531613828. The cubic root of 661973885 is about 871.5258751036.

The spelling of 661973885 in words is "six hundred sixty-one million, nine hundred seventy-three thousand, eight hundred eighty-five".