21604197 has 16 divisors (see below), whose sum is σ = 30456000. Its totient is φ = 13584384.

The previous prime is 21604181. The next prime is 21604213. The reversal of 21604197 is 79140612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21604181) and next prime (21604213).

It is not a de Polignac number, because 21604197 - 2⁴ = 21604181 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21604397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14629 + ... + 16037.

It is an arithmetic number, because the mean of its divisors is an integer number (1903500).

Almost surely, 2^21604197 is an apocalyptic number.

It is an amenable number.

21604197 is a deficient number, since it is larger than the sum of its proper divisors (8851803).

21604197 is a wasteful number, since it uses less digits than its factorization.

21604197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1700.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21604197 is about 4648.0315188260. The cubic root of 21604197 is about 278.5133665786.

The spelling of 21604197 in words is "twenty-one million, six hundred four thousand, one hundred ninety-seven".