21793831 has 4 divisors (see below), whose sum is σ = 21827464. Its totient is φ = 21760200.

The previous prime is 21793829. The next prime is 21793841. The reversal of 21793831 is 13839712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21793831 - 2¹ = 21793829 is a prime.

It is a super-2 number, since 2×21793831² = 949942139313122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21793841) 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 3 ways as a sum of consecutive naturals, for example, 15825 + ... + 17146.

It is an arithmetic number, because the mean of its divisors is an integer number (5456866).

Almost surely, 2^21793831 is an apocalyptic number.

21793831 is a deficient number, since it is larger than the sum of its proper divisors (33633).

21793831 is an equidigital number, since it uses as much as digits as its factorization.

21793831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33632.

The product of its digits is 9072, while the sum is 34.

The square root of 21793831 is about 4668.3863379116. The cubic root of 21793831 is about 279.3258911190.

The spelling of 21793831 in words is "twenty-one million, seven hundred ninety-three thousand, eight hundred thirty-one".