121890399 has 4 divisors (see below), whose sum is σ = 162520536. Its totient is φ = 81260264.

The previous prime is 121890389. The next prime is 121890421. The reversal of 121890399 is 993098121.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 121890399 - 2⁵ = 121890367 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 121890399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121890319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20315064 + ... + 20315069.

It is an arithmetic number, because the mean of its divisors is an integer number (40630134).

Almost surely, 2^121890399 is an apocalyptic number.

121890399 is a deficient number, since it is larger than the sum of its proper divisors (40630137).

121890399 is an equidigital number, since it uses as much as digits as its factorization.

121890399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40630136.

The product of its (nonzero) digits is 34992, while the sum is 42.

The square root of 121890399 is about 11040.3984982427. The cubic root of 121890399 is about 495.8190012821.

The spelling of 121890399 in words is "one hundred twenty-one million, eight hundred ninety thousand, three hundred ninety-nine".