861143440 has 20 divisors (see below), whose sum is σ = 2002158684. Its totient is φ = 344457344.

The previous prime is 861143431. The next prime is 861143443. The reversal of 861143440 is 44341168.

It can be written as a sum of positive squares in 2 ways, for example, as 223681936 + 637461504 = 14956^2 + 25248^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (861143443) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5382067 + ... + 5382226.

Almost surely, 2^861143440 is an apocalyptic number.

861143440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

861143440 is an abundant number, since it is smaller than the sum of its proper divisors (1141015244).

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

861143440 is a wasteful number, since it uses less digits than its factorization.

861143440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10764306 (or 10764300 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 31.

The square root of 861143440 is about 29345.2456115126. The cubic root of 861143440 is about 951.3898180137.

The spelling of 861143440 in words is "eight hundred sixty-one million, one hundred forty-three thousand, four hundred forty".