861861600 has 144 divisors (see below), whose sum is σ = 3117144240. Its totient is φ = 229824000.

The previous prime is 861861541. The next prime is 861861613. The reversal of 861861600 is 6168168.

It is a tau number, because it is divible by the number of its divisors (144).

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 23 ways as a sum of consecutive naturals, for example, 1650 + ... + 41550.

It is an arithmetic number, because the mean of its divisors is an integer number (21646835).

Almost surely, 2^861861600 is an apocalyptic number.

861861600 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 861861600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1558572120).

861861600 is an abundant number, since it is smaller than the sum of its proper divisors (2255282640).

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

861861600 is a wasteful number, since it uses less digits than its factorization.

861861600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39930 (or 39911 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 861861600 is about 29357.4794558388. The cubic root of 861861600 is about 951.6542185125.

The spelling of 861861600 in words is "eight hundred sixty-one million, eight hundred sixty-one thousand, six hundred".