661567860 has 72 divisors (see below), whose sum is σ = 2094019200. Its totient is φ = 168746688.

The previous prime is 661567843. The next prime is 661567861. The reversal of 661567860 is 68765166.

661567860 is a `hidden beast` number, since 6 + 6 + 1 + 567 + 86 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661567861) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 75760 + ... + 84039.

It is an arithmetic number, because the mean of its divisors is an integer number (29083600).

Almost surely, 2^661567860 is an apocalyptic number.

661567860 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661567860 is an abundant number, since it is smaller than the sum of its proper divisors (1432451340).

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

661567860 is a wasteful number, since it uses less digits than its factorization.

661567860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159837 (or 159832 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The square root of 661567860 is about 25720.9614905820. The cubic root of 661567860 is about 871.3476537399.

The spelling of 661567860 in words is "six hundred sixty-one million, five hundred sixty-seven thousand, eight hundred sixty".