121913403921 has 9 divisors (see below), whose sum is σ = 176098652041. Its totient is φ = 81274904292.

The previous prime is 121913403847. The next prime is 121913403977. The reversal of 121913403921 is 129304319121.

It is a happy number.

The square root of 121913403921 is 349161.

It is a perfect power (a square), and thus also a powerful number.

121913403921 is a `hidden beast` number, since 1 + 219 + 13 + 40 + 392 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 121913403921 - 2⁷ = 121913403793 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (121913403121) 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 8 ways as a sum of consecutive naturals, for example, 989290 + ... + 1105676.

Almost surely, 2^121913403921 is an apocalyptic number.

121913403921 is the 349161-st square number.

121913403921 is the 174581-st centered octagonal number.

It is an amenable number.

121913403921 is a deficient number, since it is larger than the sum of its proper divisors (54185248120).

121913403921 is an frugal number, since it uses more digits than its factorization.

121913403921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232780 (or 116390 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

Multiplying 121913403921 by its sum of digits (36), we get a square (4388882541156 = 2094966²).

The spelling of 121913403921 in words is "one hundred twenty-one billion, nine hundred thirteen million, four hundred three thousand, nine hundred twenty-one".