661274778 has 32 divisors (see below), whose sum is σ = 1342365696. Its totient is φ = 217137968.

The previous prime is 661274741. The next prime is 661274813. The reversal of 661274778 is 877472166.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 189001 + ... + 192467.

It is an arithmetic number, because the mean of its divisors is an integer number (41948928).

Almost surely, 2^661274778 is an apocalyptic number.

661274778 is an abundant number, since it is smaller than the sum of its proper divisors (681090918).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661274778 is a wasteful number, since it uses less digits than its factorization.

661274778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3938.

The product of its digits is 790272, while the sum is 48.

The square root of 661274778 is about 25715.2635218852. The cubic root of 661274778 is about 871.2189624651.

The spelling of 661274778 in words is "six hundred sixty-one million, two hundred seventy-four thousand, seven hundred seventy-eight".