22440 has 64 divisors (see below), whose sum is σ = 77760. Its totient is φ = 5120.

The previous prime is 22433. The next prime is 22441. The reversal of 22440 is 4422.

22440 = 28² + 29² + ... + 44².

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

22440 is an undulating number in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22441) 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, 1312 + ... + 1328.

It is an arithmetic number, because the mean of its divisors is an integer number (1215).

2²²⁴⁴⁰ is an apocalyptic number.

22440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 22440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38880).

22440 is an abundant number, since it is smaller than the sum of its proper divisors (55320).

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

22440 is a wasteful number, since it uses less digits than its factorization.

22440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42 (or 38 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 12.

The square root of 22440 is about 149.7998664886. The cubic root of 22440 is about 28.2059642332.

Adding to 22440 its reverse (4422), we get a palindrome (26862).

It can be divided in two parts, 2 and 2440, that added together give a palindrome (2442).

The spelling of 22440 in words is "twenty-two thousand, four hundred forty", and thus it is an iban number.