21921249 has 8 divisors (see below), whose sum is σ = 33403840. Its totient is φ = 12526416.

The previous prime is 21921241. The next prime is 21921253. The reversal of 21921249 is 94212912.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21921249 - 2³ = 21921241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21921241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 521914 + ... + 521955.

It is an arithmetic number, because the mean of its divisors is an integer number (4175480).

Almost surely, 2^21921249 is an apocalyptic number.

It is an amenable number.

21921249 is a deficient number, since it is larger than the sum of its proper divisors (11482591).

21921249 is a wasteful number, since it uses less digits than its factorization.

21921249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1043879.

The product of its digits is 2592, while the sum is 30.

The square root of 21921249 is about 4682.0133489771. The cubic root of 21921249 is about 279.8691948548.

The spelling of 21921249 in words is "twenty-one million, nine hundred twenty-one thousand, two hundred forty-nine".