661605740 has 24 divisors (see below), whose sum is σ = 1421684880. Its totient is φ = 258487488.

The previous prime is 661605733. The next prime is 661605757. The reversal of 661605740 is 47506166.

It is a self number, because there is not a number n which added to its sum of digits gives 661605740.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 383795 + ... + 385514.

It is an arithmetic number, because the mean of its divisors is an integer number (59236870).

Almost surely, 2^661605740 is an apocalyptic number.

It is an amenable number.

661605740 is an abundant number, since it is smaller than the sum of its proper divisors (760079140).

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

661605740 is a wasteful number, since it uses less digits than its factorization.

661605740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769361 (or 769359 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 35.

The square root of 661605740 is about 25721.6978444270. The cubic root of 661605740 is about 871.3642839407.

The spelling of 661605740 in words is "six hundred sixty-one million, six hundred five thousand, seven hundred forty".