21438438 has 32 divisors (see below), whose sum is σ = 51134976. Its totient is φ = 5858688.

The previous prime is 21438433. The next prime is 21438451. The reversal of 21438438 is 83483412.

It is a junction number, because it is equal to n+sod(n) for n = 21438399 and 21438408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21438433) 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, 10131 + ... + 12062.

It is an arithmetic number, because the mean of its divisors is an integer number (1597968).

Almost surely, 2^21438438 is an apocalyptic number.

21438438 is an abundant number, since it is smaller than the sum of its proper divisors (29696538).

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

21438438 is a wasteful number, since it uses less digits than its factorization.

21438438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22228.

The product of its digits is 18432, while the sum is 33.

The square root of 21438438 is about 4630.1660877338. The cubic root of 21438438 is about 277.7992356876.

The spelling of 21438438 in words is "twenty-one million, four hundred thirty-eight thousand, four hundred thirty-eight".