121553981 has 2 divisors, whose sum is σ = 121553982. Its totient is φ = 121553980.

The previous prime is 121553977. The next prime is 121554047. The reversal of 121553981 is 189355121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 107453956 + 14100025 = 10366^2 + 3755^2 .

It is a cyclic number.

It is not a de Polignac number, because 121553981 - 2² = 121553977 is a prime.

It is a super-2 number, since 2×121553981² = 29550740593896722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121553921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60776990 + 60776991.

It is an arithmetic number, because the mean of its divisors is an integer number (60776991).

Almost surely, 2^121553981 is an apocalyptic number.

It is an amenable number.

121553981 is a deficient number, since it is larger than the sum of its proper divisors (1).

121553981 is an equidigital number, since it uses as much as digits as its factorization.

121553981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10800, while the sum is 35.

The square root of 121553981 is about 11025.1521984959. The cubic root of 121553981 is about 495.3624268175.

The spelling of 121553981 in words is "one hundred twenty-one million, five hundred fifty-three thousand, nine hundred eighty-one".