861958125889 has 9 divisors (see below), whose sum is σ = 1002693543201. Its totient is φ = 738815680260.

The previous prime is 861958125883. The next prime is 861958125901. The reversal of 861958125889 is 988521859168.

The square root of 861958125889 is 928417.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 861958125889 - 2³⁵ = 827598387521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (861958125883) 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 8 ways as a sum of consecutive naturals, for example, 6432604 + ... + 6565234.

It is an arithmetic number, because the mean of its divisors is an integer number (111410393689).

Almost surely, 2^861958125889 is an apocalyptic number.

861958125889 is the 928417-th square number.

861958125889 is the 464209-th centered octagonal number.

It is an amenable number.

861958125889 is a deficient number, since it is larger than the sum of its proper divisors (140735417312).

861958125889 is an frugal number, since it uses more digits than its factorization.

861958125889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265276 (or 132638 counting only the distinct ones).

The product of its digits is 99532800, while the sum is 70.

The spelling of 861958125889 in words is "eight hundred sixty-one billion, nine hundred fifty-eight million, one hundred twenty-five thousand, eight hundred eighty-nine".