21226815 has 24 divisors (see below), whose sum is σ = 38394720. Its totient is φ = 10828224.

The previous prime is 21226771. The next prime is 21226823. The reversal of 21226815 is 51862212.

It is a happy number.

It is not a de Polignac number, because 21226815 - 2⁷ = 21226687 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9220 + ... + 11289.

It is an arithmetic number, because the mean of its divisors is an integer number (1599780).

Almost surely, 2^21226815 is an apocalyptic number.

21226815 is a deficient number, since it is larger than the sum of its proper divisors (17167905).

21226815 is a wasteful number, since it uses less digits than its factorization.

21226815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20543 (or 20540 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 21226815 is about 4607.2567760002. The cubic root of 21226815 is about 276.8821412959.

The spelling of 21226815 in words is "twenty-one million, two hundred twenty-six thousand, eight hundred fifteen".