21099393 has 16 divisors (see below), whose sum is σ = 35724160. Its totient is φ = 12056688.

The previous prime is 21099391. The next prime is 21099413. The reversal of 21099393 is 39399012.

It is not a de Polignac number, because 21099393 - 2¹ = 21099391 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21099391) 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 15 ways as a sum of consecutive naturals, for example, 55630 + ... + 56007.

It is an arithmetic number, because the mean of its divisors is an integer number (2232760).

Almost surely, 2^21099393 is an apocalyptic number.

It is an amenable number.

21099393 is a deficient number, since it is larger than the sum of its proper divisors (14624767).

21099393 is a wasteful number, since it uses less digits than its factorization.

21099393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111653 (or 111647 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 36.

The square root of 21099393 is about 4593.4075586649. The cubic root of 21099393 is about 276.3269990039.

The spelling of 21099393 in words is "twenty-one million, ninety-nine thousand, three hundred ninety-three".