861633520 has 80 divisors (see below), whose sum is σ = 2190083040. Its totient is φ = 312652800.

The previous prime is 861633517. The next prime is 861633533. The reversal of 861633520 is 25336168.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 623230 + ... + 624610.

It is an arithmetic number, because the mean of its divisors is an integer number (27376038).

Almost surely, 2^861633520 is an apocalyptic number.

861633520 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 861633520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1095041520).

861633520 is an abundant number, since it is smaller than the sum of its proper divisors (1328449520).

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

861633520 is a wasteful number, since it uses less digits than its factorization.

861633520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2114 (or 2108 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 861633520 is about 29353.5946691372. The cubic root of 861633520 is about 951.5702636394.

Adding to 861633520 its reverse (25336168), we get a palindrome (886969688).

The spelling of 861633520 in words is "eight hundred sixty-one million, six hundred thirty-three thousand, five hundred twenty".