1661056800 has 144 divisors (see below), whose sum is σ = 5822752320. Its totient is φ = 408867840.

The previous prime is 1661056783. The next prime is 1661056801. The reversal of 1661056800 is 86501661.

It is not an unprimeable number, because it can be changed into a prime (1661056801) 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, 4581 + ... + 57819.

It is an arithmetic number, because the mean of its divisors is an integer number (40435780).

Almost surely, 2^1661056800 is an apocalyptic number.

1661056800 is a gapful number since it is divisible by the number (10) 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 1661056800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2911376160).

1661056800 is an abundant number, since it is smaller than the sum of its proper divisors (4161695520).

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

1661056800 is a wasteful number, since it uses less digits than its factorization.

1661056800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53275 (or 53262 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 1661056800 is about 40756.0645793973. The cubic root of 1661056800 is about 1184.2993597194.

The spelling of 1661056800 in words is "one billion, six hundred sixty-one million, fifty-six thousand, eight hundred".