21943493 has 16 divisors (see below), whose sum is σ = 25958016. Its totient is φ = 18287040.

The previous prime is 21943483. The next prime is 21943507. The reversal of 21943493 is 39434912.

It is a cyclic number.

It is not a de Polignac number, because 21943493 - 2¹⁰ = 21942469 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21943483) 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 15 ways as a sum of consecutive naturals, for example, 24296 + ... + 25182.

It is an arithmetic number, because the mean of its divisors is an integer number (1622376).

Almost surely, 2^21943493 is an apocalyptic number.

It is an amenable number.

21943493 is a deficient number, since it is larger than the sum of its proper divisors (4014523).

21943493 is a wasteful number, since it uses less digits than its factorization.

21943493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1084.

The product of its digits is 23328, while the sum is 35.

The square root of 21943493 is about 4684.3882204617. The cubic root of 21943493 is about 279.9638261091.

The spelling of 21943493 in words is "twenty-one million, nine hundred forty-three thousand, four hundred ninety-three".