21927393 has 18 divisors (see below), whose sum is σ = 32814054. Its totient is φ = 14109312.

The previous prime is 21927391. The next prime is 21927407. The reversal of 21927393 is 39372912.

It can be written as a sum of positive squares in 3 ways, for example, as 831744 + 21095649 = 912^2 + 4593^2 .

It is not a de Polignac number, because 21927393 - 2¹ = 21927391 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21927391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 6121 + ... + 9017.

It is an arithmetic number, because the mean of its divisors is an integer number (1823003).

Almost surely, 2^21927393 is an apocalyptic number.

It is an amenable number.

21927393 is a deficient number, since it is larger than the sum of its proper divisors (10886661).

21927393 is a wasteful number, since it uses less digits than its factorization.

21927393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2961 (or 2929 counting only the distinct ones).

The product of its digits is 20412, while the sum is 36.

The square root of 21927393 is about 4682.6694309977. The cubic root of 21927393 is about 279.8953392853.

The spelling of 21927393 in words is "twenty-one million, nine hundred twenty-seven thousand, three hundred ninety-three".