21724044 has 12 divisors (see below), whose sum is σ = 50689464. Its totient is φ = 7241344.

The previous prime is 21724037. The next prime is 21724057. The reversal of 21724044 is 44042712.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 905157 + ... + 905180.

It is an arithmetic number, because the mean of its divisors is an integer number (4224122).

Almost surely, 2^21724044 is an apocalyptic number.

It is an amenable number.

21724044 is an abundant number, since it is smaller than the sum of its proper divisors (28965420).

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

21724044 is a wasteful number, since it uses less digits than its factorization.

21724044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1810344 (or 1810342 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 24.

The square root of 21724044 is about 4660.9059205266. The cubic root of 21724044 is about 279.0274250093.

Adding to 21724044 its reverse (44042712), we get a palindrome (65766756).

It can be divided in two parts, 2172 and 4044, that added together give a triangular number (6216 = T₁₁₁).

The spelling of 21724044 in words is "twenty-one million, seven hundred twenty-four thousand, forty-four".