21089919 has 32 divisors (see below), whose sum is σ = 30689280. Its totient is φ = 12849408.

The previous prime is 21089903. The next prime is 21089921. The reversal of 21089919 is 91998012.

It is a happy number.

It is not a de Polignac number, because 21089919 - 2⁴ = 21089903 is a prime.

It is a super-2 number, since 2×21089919² = 889569366853122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089969) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 266922 + ... + 267000.

It is an arithmetic number, because the mean of its divisors is an integer number (959040).

Almost surely, 2^21089919 is an apocalyptic number.

21089919 is a deficient number, since it is larger than the sum of its proper divisors (9599361).

21089919 is a wasteful number, since it uses less digits than its factorization.

21089919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231.

The product of its (nonzero) digits is 11664, while the sum is 39.

The square root of 21089919 is about 4592.3761823265. The cubic root of 21089919 is about 276.2856342449.

The spelling of 21089919 in words is "twenty-one million, eighty-nine thousand, nine hundred nineteen".