21562216 has 16 divisors (see below), whose sum is σ = 43539300. Its totient is φ = 9951744.

The previous prime is 21562133. The next prime is 21562217. The reversal of 21562216 is 61226512.

It can be written as a sum of positive squares in 2 ways, for example, as 21436900 + 125316 = 4630^2 + 354^2 .

It is not an unprimeable number, because it can be changed into a prime (21562217) 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, 103561 + ... + 103768.

Almost surely, 2^21562216 is an apocalyptic number.

21562216 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21562216 is an abundant number, since it is smaller than the sum of its proper divisors (21977084).

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

21562216 is a wasteful number, since it uses less digits than its factorization.

21562216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207348 (or 207344 counting only the distinct ones).

The product of its digits is 1440, while the sum is 25.

The square root of 21562216 is about 4643.5133250589. The cubic root of 21562216 is about 278.3328483942.

Adding to 21562216 its reverse (61226512), we get a palindrome (82788728).

The spelling of 21562216 in words is "twenty-one million, five hundred sixty-two thousand, two hundred sixteen".