21224516 has 12 divisors (see below), whose sum is σ = 37380588. Its totient is φ = 10544352.

The previous prime is 21224509. The next prime is 21224521. The reversal of 21224516 is 61542212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 7311616 + 13912900 = 2704^2 + 3730^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21224491 and 21224500.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16271 + ... + 17526.

It is an arithmetic number, because the mean of its divisors is an integer number (3115049).

Almost surely, 2^21224516 is an apocalyptic number.

It is an amenable number.

21224516 is a deficient number, since it is larger than the sum of its proper divisors (16156072).

21224516 is a wasteful number, since it uses less digits than its factorization.

21224516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33958 (or 33956 counting only the distinct ones).

The product of its digits is 960, while the sum is 23.

The square root of 21224516 is about 4607.0072715376. The cubic root of 21224516 is about 276.8721448987.

Adding to 21224516 its reverse (61542212), we get a palindrome (82766728).

The spelling of 21224516 in words is "twenty-one million, two hundred twenty-four thousand, five hundred sixteen".