21423733 has 4 divisors (see below), whose sum is σ = 21480640. Its totient is φ = 21366828.

The previous prime is 21423709. The next prime is 21423751. The reversal of 21423733 is 33732412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21423733 - 2⁹ = 21423221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21423698 and 21423707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423763) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27885 + ... + 28642.

It is an arithmetic number, because the mean of its divisors is an integer number (5370160).

Almost surely, 2^21423733 is an apocalyptic number.

It is an amenable number.

21423733 is a deficient number, since it is larger than the sum of its proper divisors (56907).

21423733 is an equidigital number, since it uses as much as digits as its factorization.

21423733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56906.

The product of its digits is 3024, while the sum is 25.

The square root of 21423733 is about 4628.5778593430. The cubic root of 21423733 is about 277.7357053732.

The spelling of 21423733 in words is "twenty-one million, four hundred twenty-three thousand, seven hundred thirty-three".