121423991 has 4 divisors (see below), whose sum is σ = 130764312. Its totient is φ = 112083672.

The previous prime is 121423949. The next prime is 121423999. The reversal of 121423991 is 199324121.

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 121423991 - 2¹⁴ = 121407607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121423999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4670141 + ... + 4670166.

It is an arithmetic number, because the mean of its divisors is an integer number (32691078).

Almost surely, 2^121423991 is an apocalyptic number.

121423991 is a deficient number, since it is larger than the sum of its proper divisors (9340321).

121423991 is an equidigital number, since it uses as much as digits as its factorization.

121423991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9340320.

The product of its digits is 3888, while the sum is 32.

The square root of 121423991 is about 11019.2554648669. The cubic root of 121423991 is about 495.1857834073.

The spelling of 121423991 in words is "one hundred twenty-one million, four hundred twenty-three thousand, nine hundred ninety-one".