661804560 has 320 divisors, whose sum is σ = 2458771200. Its totient is φ = 163012608.

The previous prime is 661804547. The next prime is 661804573. The reversal of 661804560 is 65408166.

It is an interprime number because it is at equal distance from previous prime (661804547) and next prime (661804573).

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2460106 + ... + 2460374.

It is an arithmetic number, because the mean of its divisors is an integer number (7683660).

Almost surely, 2^661804560 is an apocalyptic number.

661804560 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661804560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1229385600).

661804560 is an abundant number, since it is smaller than the sum of its proper divisors (1796966640).

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

661804560 is a wasteful number, since it uses less digits than its factorization.

661804560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375 (or 363 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 661804560 is about 25725.5623845233. The cubic root of 661804560 is about 871.4515601363.

The spelling of 661804560 in words is "six hundred sixty-one million, eight hundred four thousand, five hundred sixty".