861553800 has 192 divisors, whose sum is σ = 2998320000. Its totient is φ = 227370240.

The previous prime is 861553793. The next prime is 861553817. The reversal of 861553800 is 8355168.

861553800 is a `hidden beast` number, since 8 + 615 + 5 + 38 + 0 + 0 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 555426 + ... + 556974.

It is an arithmetic number, because the mean of its divisors is an integer number (15616250).

Almost surely, 2^861553800 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 861553800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1499160000).

861553800 is an abundant number, since it is smaller than the sum of its proper divisors (2136766200).

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

861553800 is a wasteful number, since it uses less digits than its factorization.

861553800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1677 (or 1662 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 861553800 is about 29352.2367120463. The cubic root of 861553800 is about 951.5409156938.

The spelling of 861553800 in words is "eight hundred sixty-one million, five hundred fifty-three thousand, eight hundred".