121872009 has 16 divisors (see below), whose sum is σ = 193784832. Its totient is φ = 66613008.

The previous prime is 121872001. The next prime is 121872011. The reversal of 121872009 is 900278121.

It is not a de Polignac number, because 121872009 - 2³ = 121872001 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (121872001) 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, 125679 + ... + 126644.

It is an arithmetic number, because the mean of its divisors is an integer number (12111552).

Almost surely, 2^121872009 is an apocalyptic number.

It is an amenable number.

121872009 is a deficient number, since it is larger than the sum of its proper divisors (71912823).

121872009 is a wasteful number, since it uses less digits than its factorization.

121872009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252356.

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 121872009 is about 11039.5656164543. The cubic root of 121872009 is about 495.7940647541.

It can be divided in two parts, 12187 and 2009, that added together give a triangular number (14196 = T₁₆₈).

The spelling of 121872009 in words is "one hundred twenty-one million, eight hundred seventy-two thousand, nine".