21445617 has 16 divisors (see below), whose sum is σ = 29063232. Its totient is φ = 14064960.

The previous prime is 21445609. The next prime is 21445643. The reversal of 21445617 is 71654412.

It is not a de Polignac number, because 21445617 - 2³ = 21445609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21445657) 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, 77283 + ... + 77559.

It is an arithmetic number, because the mean of its divisors is an integer number (1816452).

Almost surely, 2^21445617 is an apocalyptic number.

It is an amenable number.

21445617 is a deficient number, since it is larger than the sum of its proper divisors (7617615).

21445617 is a wasteful number, since it uses less digits than its factorization.

21445617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 608.

The product of its digits is 6720, while the sum is 30.

The square root of 21445617 is about 4630.9412650130. The cubic root of 21445617 is about 277.8302407161.

The spelling of 21445617 in words is "twenty-one million, four hundred forty-five thousand, six hundred seventeen".