861898881121 has 2 divisors, whose sum is σ = 861898881122. Its totient is φ = 861898881120.

The previous prime is 861898881113. The next prime is 861898881139. The reversal of 861898881121 is 121188898168.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 756832141521 + 105066739600 = 869961^2 + 324140^2 .

It is a cyclic number.

It is not a de Polignac number, because 861898881121 - 2³ = 861898881113 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 861898881121.

It is not a weakly prime, because it can be changed into another prime (861898881191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430949440560 + 430949440561.

It is an arithmetic number, because the mean of its divisors is an integer number (430949440561).

Almost surely, 2^861898881121 is an apocalyptic number.

It is an amenable number.

861898881121 is a deficient number, since it is larger than the sum of its proper divisors (1).

861898881121 is an equidigital number, since it uses as much as digits as its factorization.

861898881121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3538944, while the sum is 61.

The spelling of 861898881121 in words is "eight hundred sixty-one billion, eight hundred ninety-eight million, eight hundred eighty-one thousand, one hundred twenty-one".