861188721 has 32 divisors (see below), whose sum is σ = 1198540800. Its totient is φ = 549700800.

The previous prime is 861188681. The next prime is 861188761. The reversal of 861188721 is 127881168.

861188721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (861188681) and next prime (861188761).

It is not a de Polignac number, because 861188721 - 2⁷ = 861188593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (861188761) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1197400 + ... + 1198118.

It is an arithmetic number, because the mean of its divisors is an integer number (37454400).

Almost surely, 2^861188721 is an apocalyptic number.

It is an amenable number.

861188721 is a deficient number, since it is larger than the sum of its proper divisors (337352079).

861188721 is a wasteful number, since it uses less digits than its factorization.

861188721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 949.

The product of its digits is 43008, while the sum is 42.

The square root of 861188721 is about 29346.0171232827. The cubic root of 861188721 is about 951.4064931789.

The spelling of 861188721 in words is "eight hundred sixty-one million, one hundred eighty-eight thousand, seven hundred twenty-one".