121990405 has 8 divisors (see below), whose sum is σ = 146448000. Its totient is φ = 97552656.

The previous prime is 121990403. The next prime is 121990409. The reversal of 121990405 is 504099121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 121990405 - 2¹ = 121990403 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121990403) 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 in 7 ways as a sum of consecutive naturals, for example, 19896 + ... + 25294.

It is an arithmetic number, because the mean of its divisors is an integer number (18306000).

Almost surely, 2^121990405 is an apocalyptic number.

It is an amenable number.

121990405 is a deficient number, since it is larger than the sum of its proper divisors (24457595).

121990405 is an equidigital number, since it uses as much as digits as its factorization.

121990405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9923.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 121990405 is about 11044.9266634052. The cubic root of 121990405 is about 495.9545638335.

The spelling of 121990405 in words is "one hundred twenty-one million, nine hundred ninety thousand, four hundred five".