21222613 has 8 divisors (see below), whose sum is σ = 22588632. Its totient is φ = 19869696.

The previous prime is 21222611. The next prime is 21222653. The reversal of 21222613 is 31622212.

21222613 = 3257² + 3258².

It can be written as a sum of positive squares in 4 ways, for example, as 10608049 + 10614564 = 3257^2 + 3258^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21222613 - 2¹ = 21222611 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 181 + ... + 6517.

It is an arithmetic number, because the mean of its divisors is an integer number (2823579).

Almost surely, 2^21222613 is an apocalyptic number.

21222613 is the 3258-th centered square number.

It is an amenable number.

21222613 is a deficient number, since it is larger than the sum of its proper divisors (1366019).

21222613 is a wasteful number, since it uses less digits than its factorization.

21222613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6551.

The product of its digits is 288, while the sum is 19.

The square root of 21222613 is about 4606.8007336980. The cubic root of 21222613 is about 276.8638698228.

Adding to 21222613 its reverse (31622212), we get a palindrome (52844825).

The spelling of 21222613 in words is "twenty-one million, two hundred twenty-two thousand, six hundred thirteen".