661665994 has 48 divisors (see below), whose sum is σ = 1157163840. Its totient is φ = 282744000.

The previous prime is 661665971. The next prime is 661666009. The reversal of 661665994 is 499566166.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 693822 + ... + 694774.

It is an arithmetic number, because the mean of its divisors is an integer number (24107580).

Almost surely, 2^661665994 is an apocalyptic number.

661665994 is a deficient number, since it is larger than the sum of its proper divisors (495497846).

661665994 is a wasteful number, since it uses less digits than its factorization.

661665994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1147 (or 1136 counting only the distinct ones).

The product of its digits is 2099520, while the sum is 52.

The square root of 661665994 is about 25722.8690856988. The cubic root of 661665994 is about 871.3907355400.

The spelling of 661665994 in words is "six hundred sixty-one million, six hundred sixty-five thousand, nine hundred ninety-four".