661253566 has 16 divisors (see below), whose sum is σ = 1024399440. Its totient is φ = 319887360.

The previous prime is 661253557. The next prime is 661253581. The reversal of 661253566 is 665352166.

It is a happy number.

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, 11715 + ... + 38206.

It is an arithmetic number, because the mean of its divisors is an integer number (64024965).

Almost surely, 2^661253566 is an apocalyptic number.

661253566 is a deficient number, since it is larger than the sum of its proper divisors (363145874).

661253566 is a wasteful number, since it uses less digits than its factorization.

661253566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50139.

The product of its digits is 194400, while the sum is 40.

The square root of 661253566 is about 25714.8510787055. The cubic root of 661253566 is about 871.2096468750.

The spelling of 661253566 in words is "six hundred sixty-one million, two hundred fifty-three thousand, five hundred sixty-six".