121989621 has 16 divisors (see below), whose sum is σ = 175904960. Its totient is φ = 74753280.

The previous prime is 121989613. The next prime is 121989641. The reversal of 121989621 is 126989121.

It is not a de Polignac number, because 121989621 - 2³ = 121989613 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 121989621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121989601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2910 + ... + 15888.

It is an arithmetic number, because the mean of its divisors is an integer number (10994060).

Almost surely, 2^121989621 is an apocalyptic number.

It is an amenable number.

121989621 is a deficient number, since it is larger than the sum of its proper divisors (53915339).

121989621 is a wasteful number, since it uses less digits than its factorization.

121989621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13236.

The product of its digits is 15552, while the sum is 39.

The square root of 121989621 is about 11044.8911719401. The cubic root of 121989621 is about 495.9535013751.

The spelling of 121989621 in words is "one hundred twenty-one million, nine hundred eighty-nine thousand, six hundred twenty-one".