861899520 has 144 divisors (see below), whose sum is σ = 2764550880. Its totient is φ = 228851712.

The previous prime is 861899513. The next prime is 861899531. The reversal of 861899520 is 25998168.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 861899520.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1493472 + ... + 1494048.

It is an arithmetic number, because the mean of its divisors is an integer number (19198270).

Almost surely, 2^861899520 is an apocalyptic number.

861899520 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 861899520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1382275440).

861899520 is an abundant number, since it is smaller than the sum of its proper divisors (1902651360).

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

861899520 is a wasteful number, since it uses less digits than its factorization.

861899520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990 (or 976 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 48.

The square root of 861899520 is about 29358.1252807464. The cubic root of 861899520 is about 951.6681751998.

The spelling of 861899520 in words is "eight hundred sixty-one million, eight hundred ninety-nine thousand, five hundred twenty".