661919975 has 12 divisors (see below), whose sum is σ = 822221184. Its totient is φ = 528606720.

The previous prime is 661919959. The next prime is 661920011. The reversal of 661919975 is 579919166.

It is a happy number.

It is not a de Polignac number, because 661919975 - 2⁴ = 661919959 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 11 ways as a sum of consecutive naturals, for example, 8519 + ... + 37368.

It is an arithmetic number, because the mean of its divisors is an integer number (68518432).

Almost surely, 2^661919975 is an apocalyptic number.

661919975 is a deficient number, since it is larger than the sum of its proper divisors (160301209).

661919975 is a wasteful number, since it uses less digits than its factorization.

661919975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46474 (or 46469 counting only the distinct ones).

The product of its digits is 918540, while the sum is 53.

The square root of 661919975 is about 25727.8054835619. The cubic root of 661919975 is about 871.5022159450.

The spelling of 661919975 in words is "six hundred sixty-one million, nine hundred nineteen thousand, nine hundred seventy-five".