21322240 has 40 divisors (see below), whose sum is σ = 51129540. Its totient is φ = 8527872.

The previous prime is 21322229. The next prime is 21322241. The reversal of 21322240 is 4222312.

It can be written as a sum of positive squares in 2 ways, for example, as 19642624 + 1679616 = 4432^2 + 1296^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is not an unprimeable number, because it can be changed into a prime (21322241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1605 + ... + 6724.

Almost surely, 2^21322240 is an apocalyptic number.

21322240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21322240 is an abundant number, since it is smaller than the sum of its proper divisors (29807300).

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

21322240 is an frugal number, since it uses more digits than its factorization.

21322240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8352 (or 8336 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21322240 is about 4617.6011088010. The cubic root of 21322240 is about 277.2964283568.

Adding to 21322240 its reverse (4222312), we get a palindrome (25544552).

The spelling of 21322240 in words is "twenty-one million, three hundred twenty-two thousand, two hundred forty".