1561618800 has 360 divisors, whose sum is σ = 6396416000. Its totient is φ = 345254400.

The previous prime is 1561618753. The next prime is 1561618841. The reversal of 1561618800 is 88161651.

1561618800 is a `hidden beast` number, since 1 + 561 + 6 + 18 + 80 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (360).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 780201 + ... + 782199.

Almost surely, 2^1561618800 is an apocalyptic number.

1561618800 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 1561618800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3198208000).

1561618800 is an abundant number, since it is smaller than the sum of its proper divisors (4834797200).

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

1561618800 is a wasteful number, since it uses less digits than its factorization.

1561618800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2061 (or 2047 counting only the distinct ones).

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

The square root of 1561618800 is about 39517.3227838122. The cubic root of 1561618800 is about 1160.1790250843.

The spelling of 1561618800 in words is "one billion, five hundred sixty-one million, six hundred eighteen thousand, eight hundred".