21089215 has 16 divisors (see below), whose sum is σ = 29090880. Its totient is φ = 14376960.

The previous prime is 21089213. The next prime is 21089273. The reversal of 21089215 is 51298012.

It is not a de Polignac number, because 21089215 - 2¹ = 21089213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089213) 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, 4671 + ... + 7999.

It is an arithmetic number, because the mean of its divisors is an integer number (1818180).

Almost surely, 2^21089215 is an apocalyptic number.

21089215 is a deficient number, since it is larger than the sum of its proper divisors (8001665).

21089215 is a wasteful number, since it uses less digits than its factorization.

21089215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3522.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 21089215 is about 4592.2995329138. The cubic root of 21089215 is about 276.2825599918.

The spelling of 21089215 in words is "twenty-one million, eighty-nine thousand, two hundred fifteen".