21244220 has 24 divisors (see below), whose sum is σ = 47237904. Its totient is φ = 7997696.

The previous prime is 21244219. The next prime is 21244229. The reversal of 21244220 is 2244212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21244229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30902 + ... + 31581.

It is an arithmetic number, because the mean of its divisors is an integer number (1968246).

Almost surely, 2^21244220 is an apocalyptic number.

21244220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21244220 is an abundant number, since it is smaller than the sum of its proper divisors (25993684).

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

21244220 is a wasteful number, since it uses less digits than its factorization.

21244220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62509 (or 62507 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21244220 is about 4609.1452569864. The cubic root of 21244220 is about 276.9577974430.

Adding to 21244220 its reverse (2244212), we get a palindrome (23488432).

The spelling of 21244220 in words is "twenty-one million, two hundred forty-four thousand, two hundred twenty".