661561116 has 24 divisors (see below), whose sum is σ = 1544298000. Its totient is φ = 220426752.

The previous prime is 661561097. The next prime is 661561127. The reversal of 661561116 is 611165166.

It is a super-2 number, since 2×661561116² = 875326220406330912, which contains 22 as substring.

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, 21510 + ... + 42258.

It is an arithmetic number, because the mean of its divisors is an integer number (64345750).

Almost surely, 2^661561116 is an apocalyptic number.

It is an amenable number.

661561116 is an abundant number, since it is smaller than the sum of its proper divisors (882736884).

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

661561116 is a wasteful number, since it uses less digits than its factorization.

661561116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23413 (or 23411 counting only the distinct ones).

The product of its digits is 6480, while the sum is 33.

The square root of 661561116 is about 25720.8303909497. The cubic root of 661561116 is about 871.3446929005.

The spelling of 661561116 in words is "six hundred sixty-one million, five hundred sixty-one thousand, one hundred sixteen".