861444864 has 216 divisors, whose sum is σ = 2931848192. Its totient is φ = 238049280.

The previous prime is 861444863. The next prime is 861444869. The reversal of 861444864 is 468444168.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (861444863) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 499107 + ... + 500829.

Almost surely, 2^861444864 is an apocalyptic number.

861444864 is a gapful number since it is divisible by the number (84) 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 861444864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1465924096).

861444864 is an abundant number, since it is smaller than the sum of its proper divisors (2070403328).

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

861444864 is a wasteful number, since it uses less digits than its factorization.

861444864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1783 (or 1766 counting only the distinct ones).

The product of its digits is 589824, while the sum is 45.

The square root of 861444864 is about 29350.3809856022. The cubic root of 861444864 is about 951.5008093068.

The spelling of 861444864 in words is "eight hundred sixty-one million, four hundred forty-four thousand, eight hundred sixty-four".