21273438 has 16 divisors (see below), whose sum is σ = 43182720. Its totient is φ = 6985176.

The previous prime is 21273437. The next prime is 21273449. The reversal of 21273438 is 83437212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21273431) 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 7 ways as a sum of consecutive naturals, for example, 26058 + ... + 26861.

It is an arithmetic number, because the mean of its divisors is an integer number (2698920).

Almost surely, 2^21273438 is an apocalyptic number.

21273438 is an abundant number, since it is smaller than the sum of its proper divisors (21909282).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21273438 is a wasteful number, since it uses less digits than its factorization.

21273438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52991.

The product of its digits is 8064, while the sum is 30.

The square root of 21273438 is about 4612.3137360765. The cubic root of 21273438 is about 277.0847095465.

It can be divided in two parts, 2127 and 3438, that added together give a triangular number (5565 = T₁₀₅).

The spelling of 21273438 in words is "twenty-one million, two hundred seventy-three thousand, four hundred thirty-eight".