861397505520 has 160 divisors (see below), whose sum is σ = 2681598104832. Its totient is φ = 228738041856.

The previous prime is 861397505503. The next prime is 861397505533. The reversal of 861397505520 is 25505793168.

It is a happy number.

861397505520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 126803244 + ... + 126810036.

Almost surely, 2^861397505520 is an apocalyptic number.

861397505520 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 861397505520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1340799052416).

861397505520 is an abundant number, since it is smaller than the sum of its proper divisors (1820200599312).

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

861397505520 is a wasteful number, since it uses less digits than its factorization.

861397505520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8959 (or 8953 counting only the distinct ones).

The product of its (nonzero) digits is 2268000, while the sum is 51.

The spelling of 861397505520 in words is "eight hundred sixty-one billion, three hundred ninety-seven million, five hundred five thousand, five hundred twenty".