861212991 has 8 divisors (see below), whose sum is σ = 1151575600. Its totient is φ = 572496192.

The previous prime is 861212983. The next prime is 861212993. The reversal of 861212991 is 199212168.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 861212991 - 2³ = 861212983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861212993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 410230 + ... + 412323.

It is an arithmetic number, because the mean of its divisors is an integer number (143946950).

Almost surely, 2^861212991 is an apocalyptic number.

861212991 is a deficient number, since it is larger than the sum of its proper divisors (290362609).

861212991 is a wasteful number, since it uses less digits than its factorization.

861212991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 822905.

The product of its digits is 15552, while the sum is 39.

The square root of 861212991 is about 29346.4306347467. The cubic root of 861212991 is about 951.4154306000.

The spelling of 861212991 in words is "eight hundred sixty-one million, two hundred twelve thousand, nine hundred ninety-one".