21915393 has 8 divisors (see below), whose sum is σ = 29256000. Its totient is φ = 14592528.

The previous prime is 21915391. The next prime is 21915407. The reversal of 21915393 is 39351912.

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

It is not a de Polignac number, because 21915393 - 2¹ = 21915391 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21915391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1218 + ... + 6731.

It is an arithmetic number, because the mean of its divisors is an integer number (3657000).

Almost surely, 2^21915393 is an apocalyptic number.

It is an amenable number.

21915393 is a deficient number, since it is larger than the sum of its proper divisors (7340607).

21915393 is an equidigital number, since it uses as much as digits as its factorization.

21915393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8871.

The product of its digits is 7290, while the sum is 33.

The square root of 21915393 is about 4681.3879352175. The cubic root of 21915393 is about 279.8442713971.

The spelling of 21915393 in words is "twenty-one million, nine hundred fifteen thousand, three hundred ninety-three".