21943915 has 12 divisors (see below), whose sum is σ = 30632256. Its totient is φ = 15047088.

The previous prime is 21943913. The next prime is 21943919. The reversal of 21943915 is 51934912.

It is not a de Polignac number, because 21943915 - 2¹ = 21943913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21943913) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 44539 + ... + 45028.

It is an arithmetic number, because the mean of its divisors is an integer number (2552688).

Almost surely, 2^21943915 is an apocalyptic number.

21943915 is a deficient number, since it is larger than the sum of its proper divisors (8688341).

21943915 is an equidigital number, since it uses as much as digits as its factorization.

21943915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89586 (or 89579 counting only the distinct ones).

The product of its digits is 9720, while the sum is 34.

The square root of 21943915 is about 4684.4332634802. The cubic root of 21943915 is about 279.9656207790.

The spelling of 21943915 in words is "twenty-one million, nine hundred forty-three thousand, nine hundred fifteen".