21718044 has 60 divisors (see below), whose sum is σ = 60130224. Its totient is φ = 6811776.

The previous prime is 21718043. The next prime is 21718051. The reversal of 21718044 is 44081712.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21717999 and 21718017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21718043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3537 + ... + 7479.

Almost surely, 2^21718044 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21718044, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30065112).

21718044 is an abundant number, since it is smaller than the sum of its proper divisors (38412180).

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

21718044 is a wasteful number, since it uses less digits than its factorization.

21718044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3976 (or 3965 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 21718044 is about 4660.2622243818. The cubic root of 21718044 is about 279.0017342938.

Adding to 21718044 its reverse (44081712), we get a palindrome (65799756).

The spelling of 21718044 in words is "twenty-one million, seven hundred eighteen thousand, forty-four".