661475661 has 48 divisors (see below), whose sum is σ = 1173174912. Its totient is φ = 323389440.

The previous prime is 661475641. The next prime is 661475663. The reversal of 661475661 is 166574166.

It is a happy number.

It is not a de Polignac number, because 661475661 - 2⁶ = 661475597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661475663) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 35541 + ... + 50853.

It is an arithmetic number, because the mean of its divisors is an integer number (24441144).

Almost surely, 2^661475661 is an apocalyptic number.

It is an amenable number.

661475661 is a deficient number, since it is larger than the sum of its proper divisors (511699251).

661475661 is a wasteful number, since it uses less digits than its factorization.

661475661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15362 (or 15351 counting only the distinct ones).

The product of its digits is 181440, while the sum is 42.

The square root of 661475661 is about 25719.1691351023. The cubic root of 661475661 is about 871.3071735818.

The spelling of 661475661 in words is "six hundred sixty-one million, four hundred seventy-five thousand, six hundred sixty-one".