661519872 has 240 divisors, whose sum is σ = 2137415280. Its totient is φ = 203046912.

The previous prime is 661519843. The next prime is 661519883. The reversal of 661519872 is 278915166.

661519872 is a `hidden beast` number, since 6 + 61 + 519 + 8 + 72 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1617204 + ... + 1617612.

It is an arithmetic number, because the mean of its divisors is an integer number (8905897).

Almost surely, 2^661519872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661519872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1068707640).

661519872 is an abundant number, since it is smaller than the sum of its proper divisors (1475895408).

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

661519872 is an equidigital number, since it uses as much as digits as its factorization.

661519872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455 (or 427 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 661519872 is about 25720.0286158472. The cubic root of 661519872 is about 871.3265849805.

The spelling of 661519872 in words is "six hundred sixty-one million, five hundred nineteen thousand, eight hundred seventy-two".