861638800 has 120 divisors (see below), whose sum is σ = 2331493632. Its totient is φ = 303168000.

The previous prime is 861638779. The next prime is 861638801. The reversal of 861638800 is 8836168.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (861638801) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 133242 + ... + 139558.

Almost surely, 2^861638800 is an apocalyptic number.

861638800 is a gapful number since it is divisible by the number (80) 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 861638800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1165746816).

861638800 is an abundant number, since it is smaller than the sum of its proper divisors (1469854832).

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

861638800 is a wasteful number, since it uses less digits than its factorization.

861638800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6377 (or 6366 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 40.

The square root of 861638800 is about 29353.6846068769. The cubic root of 861638800 is about 951.5722073431.

The spelling of 861638800 in words is "eight hundred sixty-one million, six hundred thirty-eight thousand, eight hundred".