121985921 has 2 divisors, whose sum is σ = 121985922. Its totient is φ = 121985920.

The previous prime is 121985893. The next prime is 121985957. The reversal of 121985921 is 129589121.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 94789696 + 27196225 = 9736^2 + 5215^2 .

It is an emirp because it is prime and its reverse (129589121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 121985921 - 2¹⁴ = 121969537 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (121985021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60992960 + 60992961.

It is an arithmetic number, because the mean of its divisors is an integer number (60992961).

Almost surely, 2^121985921 is an apocalyptic number.

It is an amenable number.

121985921 is a deficient number, since it is larger than the sum of its proper divisors (1).

121985921 is an equidigital number, since it uses as much as digits as its factorization.

121985921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 38.

The square root of 121985921 is about 11044.7236724148. The cubic root of 121985921 is about 495.9484871602.

The spelling of 121985921 in words is "one hundred twenty-one million, nine hundred eighty-five thousand, nine hundred twenty-one".