661115880 has 48 divisors (see below), whose sum is σ = 2148627780. Its totient is φ = 176297472.

The previous prime is 661115869. The next prime is 661115881. The reversal of 661115880 is 88511166.

661115880 is a `hidden beast` number, since 6 + 61 + 11 + 588 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 622103364 + 39012516 = 24942^2 + 6246^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (661115881) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 917857 + ... + 918576.

Almost surely, 2^661115880 is an apocalyptic number.

661115880 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661115880 is an abundant number, since it is smaller than the sum of its proper divisors (1487511900).

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

661115880 is a wasteful number, since it uses less digits than its factorization.

661115880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1836450 (or 1836443 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 36.

The square root of 661115880 is about 25712.1737704147. The cubic root of 661115880 is about 871.1491750156.

The spelling of 661115880 in words is "six hundred sixty-one million, one hundred fifteen thousand, eight hundred eighty".