21544429 has 4 divisors (see below), whose sum is σ = 21578076. Its totient is φ = 21510784.

The previous prime is 21544427. The next prime is 21544451. The reversal of 21544429 is 92444512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2856100 + 18688329 = 1690^2 + 4323^2 .

It is a cyclic number.

It is not a de Polignac number, because 21544429 - 2¹ = 21544427 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21544429.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21544421) 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, 15844 + ... + 17149.

It is an arithmetic number, because the mean of its divisors is an integer number (5394519).

Almost surely, 2^21544429 is an apocalyptic number.

It is an amenable number.

21544429 is a deficient number, since it is larger than the sum of its proper divisors (33647).

21544429 is an equidigital number, since it uses as much as digits as its factorization.

21544429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33646.

The product of its digits is 11520, while the sum is 31.

The square root of 21544429 is about 4641.5976775244. The cubic root of 21544429 is about 278.2562936730.

It can be divided in two parts, 215 and 44429, that added together give a palindrome (44644).

The spelling of 21544429 in words is "twenty-one million, five hundred forty-four thousand, four hundred twenty-nine".