20121609 has 8 divisors (see below), whose sum is σ = 27335232. Its totient is φ = 13161200.

The previous prime is 20121581. The next prime is 20121623. The reversal of 20121609 is 90612102.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20121609 - 2⁹ = 20121097 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20131609) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63117 + ... + 63434.

It is an arithmetic number, because the mean of its divisors is an integer number (3416904).

Almost surely, 2^20121609 is an apocalyptic number.

It is an amenable number.

20121609 is a deficient number, since it is larger than the sum of its proper divisors (7213623).

20121609 is a wasteful number, since it uses less digits than its factorization.

20121609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126607.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 20121609 is about 4485.7116492258. The cubic root of 20121609 is about 271.9908130187.

The spelling of 20121609 in words is "twenty million, one hundred twenty-one thousand, six hundred nine".