121663591 has 4 divisors (see below), whose sum is σ = 139044112. Its totient is φ = 104283072.

The previous prime is 121663571. The next prime is 121663603. The reversal of 121663591 is 195366121.

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 121663591 - 2⁵ = 121663559 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 (121663501) 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, 8690250 + ... + 8690263.

It is an arithmetic number, because the mean of its divisors is an integer number (34761028).

Almost surely, 2^121663591 is an apocalyptic number.

121663591 is a deficient number, since it is larger than the sum of its proper divisors (17380521).

121663591 is an equidigital number, since it uses as much as digits as its factorization.

121663591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17380520.

The product of its digits is 9720, while the sum is 34.

The square root of 121663591 is about 11030.1219848196. The cubic root of 121663591 is about 495.5112780051.

The spelling of 121663591 in words is "one hundred twenty-one million, six hundred sixty-three thousand, five hundred ninety-one".