21056423 has 16 divisors (see below), whose sum is σ = 22394880. Its totient is φ = 19777056.

The previous prime is 21056401. The next prime is 21056437. The reversal of 21056423 is 32465012.

It is not a de Polignac number, because 21056423 - 2¹⁰ = 21055399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 196736 + ... + 196842.

It is an arithmetic number, because the mean of its divisors is an integer number (1399680).

Almost surely, 2^21056423 is an apocalyptic number.

21056423 is a deficient number, since it is larger than the sum of its proper divisors (1338457).

21056423 is a wasteful number, since it uses less digits than its factorization.

21056423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21056423 is about 4588.7278193417. The cubic root of 21056423 is about 276.1392867982.

The spelling of 21056423 in words is "twenty-one million, fifty-six thousand, four hundred twenty-three".