21136609 has 16 divisors (see below), whose sum is σ = 23933952. Its totient is φ = 18520128.

The previous prime is 21136603. The next prime is 21136613. The reversal of 21136609 is 90663112.

It is a cyclic number.

It is not a de Polignac number, because 21136609 - 2³ = 21136601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21136601) 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, 66519 + ... + 66835.

It is an arithmetic number, because the mean of its divisors is an integer number (1495872).

Almost surely, 2^21136609 is an apocalyptic number.

It is an amenable number.

21136609 is a deficient number, since it is larger than the sum of its proper divisors (2797343).

21136609 is a wasteful number, since it uses less digits than its factorization.

21136609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 576.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21136609 is about 4597.4567969694. The cubic root of 21136609 is about 276.4893693177.

The spelling of 21136609 in words is "twenty-one million, one hundred thirty-six thousand, six hundred nine".