21344420 has 12 divisors (see below), whose sum is σ = 44823324. Its totient is φ = 8537760.

The previous prime is 21344419. The next prime is 21344447. The reversal of 21344420 is 2444312.

It can be written as a sum of positive squares in 2 ways, for example, as 7086244 + 14258176 = 2662^2 + 3776^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 1067221 = 21344420 / (2 + 1 + 3 + 4 + 4 + 4 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 21344392 and 21344401.

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, 533591 + ... + 533630.

It is an arithmetic number, because the mean of its divisors is an integer number (3735277).

Almost surely, 2^21344420 is an apocalyptic number.

21344420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21344420 is an abundant number, since it is smaller than the sum of its proper divisors (23478904).

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

21344420 is a wasteful number, since it uses less digits than its factorization.

It is an anagram of its base 9 representation: 21344420 = (44142032)₉.

21344420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1067230 (or 1067228 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21344420 is about 4620.0021645017. The cubic root of 21344420 is about 277.3925455783.

Subtracting from 21344420 its sum of digits (20), we obtain a square (21344400 = 4620²).

Adding to 21344420 its reverse (2444312), we get a palindrome (23788732).

The spelling of 21344420 in words is "twenty-one million, three hundred forty-four thousand, four hundred twenty".