21226015 has 4 divisors (see below), whose sum is σ = 25471224. Its totient is φ = 16980808.

The previous prime is 21226001. The next prime is 21226019. The reversal of 21226015 is 51062212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21226015 - 2¹⁵ = 21193247 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21225983 and 21226001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21226019) 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 3 ways as a sum of consecutive naturals, for example, 2122597 + ... + 2122606.

It is an arithmetic number, because the mean of its divisors is an integer number (6367806).

Almost surely, 2^21226015 is an apocalyptic number.

21226015 is a deficient number, since it is larger than the sum of its proper divisors (4245209).

21226015 is an equidigital number, since it uses as much as digits as its factorization.

21226015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4245208.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21226015 is about 4607.1699556235. The cubic root of 21226015 is about 276.8786628577.

Adding to 21226015 its reverse (51062212), we get a palindrome (72288227).

The spelling of 21226015 in words is "twenty-one million, two hundred twenty-six thousand, fifteen".