121561621 has 2 divisors, whose sum is σ = 121561622. Its totient is φ = 121561620.

The previous prime is 121561603. The next prime is 121561637. The reversal of 121561621 is 126165121.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 84180625 + 37380996 = 9175^2 + 6114^2 .

It is an emirp because it is prime and its reverse (126165121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 121561621 - 2⁵ = 121561589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121561691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60780810 + 60780811.

It is an arithmetic number, because the mean of its divisors is an integer number (60780811).

Almost surely, 2^121561621 is an apocalyptic number.

It is an amenable number.

121561621 is a deficient number, since it is larger than the sum of its proper divisors (1).

121561621 is an equidigital number, since it uses as much as digits as its factorization.

121561621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 720, while the sum is 25.

The square root of 121561621 is about 11025.4986735295. The cubic root of 121561621 is about 495.3728048943.

The spelling of 121561621 in words is "one hundred twenty-one million, five hundred sixty-one thousand, six hundred twenty-one".