121199999981 has 2 divisors, whose sum is σ = 121199999982. Its totient is φ = 121199999980.

The previous prime is 121199999957. The next prime is 121200000023. The reversal of 121199999981 is 189999991121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120918934756 + 281065225 = 347734^2 + 16765^2 .

It is a cyclic number.

It is not a de Polignac number, because 121199999981 - 2³⁰ = 120126258157 is a prime.

It is a super-2 number, since 2×121199999981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121199999381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60599999990 + 60599999991.

It is an arithmetic number, because the mean of its divisors is an integer number (60599999991).

Almost surely, 2^121199999981 is an apocalyptic number.

It is an amenable number.

121199999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

121199999981 is an equidigital number, since it uses as much as digits as its factorization.

121199999981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8503056, while the sum is 68.

The spelling of 121199999981 in words is "one hundred twenty-one billion, one hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred eighty-one".