861312990 has 128 divisors (see below), whose sum is σ = 2280296448. Its totient is φ = 207267840.

The previous prime is 861312967. The next prime is 861313009. The reversal of 861312990 is 99213168.

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 63 ways as a sum of consecutive naturals, for example, 2481997 + ... + 2482343.

It is an arithmetic number, because the mean of its divisors is an integer number (17814816).

Almost surely, 2^861312990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 861312990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1140148224).

861312990 is an abundant number, since it is smaller than the sum of its proper divisors (1418983458).

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

861312990 is a wasteful number, since it uses less digits than its factorization.

861312990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562.

The product of its (nonzero) digits is 23328, while the sum is 39.

The square root of 861312990 is about 29348.1343529704. The cubic root of 861312990 is about 951.4522534342.

The spelling of 861312990 in words is "eight hundred sixty-one million, three hundred twelve thousand, nine hundred ninety".