21652240 has 20 divisors (see below), whose sum is σ = 50341644. Its totient is φ = 8660864.

The previous prime is 21652219. The next prime is 21652273. The reversal of 21652240 is 4225612.

It can be written as a sum of positive squares in 2 ways, for example, as 15241216 + 6411024 = 3904^2 + 2532^2 .

It is a tau number, because it is divible by the number of its divisors (20).

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, 135247 + ... + 135406.

Almost surely, 2^21652240 is an apocalyptic number.

21652240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21652240 is an abundant number, since it is smaller than the sum of its proper divisors (28689404).

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

21652240 is a wasteful number, since it uses less digits than its factorization.

21652240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270666 (or 270660 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21652240 is about 4653.1967506221. The cubic root of 21652240 is about 278.7196646324.

Adding to 21652240 its reverse (4225612), we get a palindrome (25877852).

The spelling of 21652240 in words is "twenty-one million, six hundred fifty-two thousand, two hundred forty".