661761790 has 16 divisors (see below), whose sum is σ = 1207489968. Its totient is φ = 261078336.

The previous prime is 661761769. The next prime is 661761803. The reversal of 661761790 is 97167166.

It is a congruent number.

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, 452532 + ... + 453991.

It is an arithmetic number, because the mean of its divisors is an integer number (75468123).

Almost surely, 2^661761790 is an apocalyptic number.

661761790 is a deficient number, since it is larger than the sum of its proper divisors (545728178).

661761790 is a wasteful number, since it uses less digits than its factorization.

661761790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906603.

The product of its (nonzero) digits is 95256, while the sum is 43.

The square root of 661761790 is about 25724.7310967481. The cubic root of 661761790 is about 871.4327868265.

The spelling of 661761790 in words is "six hundred sixty-one million, seven hundred sixty-one thousand, seven hundred ninety".