861325991 has 16 divisors (see below), whose sum is σ = 906843168. Its totient is φ = 817152000.

The previous prime is 861325981. The next prime is 861326003. The reversal of 861325991 is 199523168.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-861325991 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861325981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 452141 + ... + 454041.

It is an arithmetic number, because the mean of its divisors is an integer number (56677698).

Almost surely, 2^861325991 is an apocalyptic number.

861325991 is a deficient number, since it is larger than the sum of its proper divisors (45517177).

861325991 is a wasteful number, since it uses less digits than its factorization.

861325991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2242.

The product of its digits is 116640, while the sum is 44.

The square root of 861325991 is about 29348.3558483265. The cubic root of 861325991 is about 951.4570406094.

The spelling of 861325991 in words is "eight hundred sixty-one million, three hundred twenty-five thousand, nine hundred ninety-one".