21005226 has 24 divisors (see below), whose sum is σ = 49649184. Its totient is φ = 6365160.

The previous prime is 21005219. The next prime is 21005227. The reversal of 21005226 is 62250012.

It is a super-2 number, since 2×21005226² = 882439038622152, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21005199 and 21005208.

It is not an unprimeable number, because it can be changed into a prime (21005227) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52846 + ... + 53241.

It is an arithmetic number, because the mean of its divisors is an integer number (2068716).

Almost surely, 2^21005226 is an apocalyptic number.

21005226 is an abundant number, since it is smaller than the sum of its proper divisors (28643958).

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

21005226 is a wasteful number, since it uses less digits than its factorization.

21005226 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106106 (or 106103 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21005226 is about 4583.1458628326. The cubic root of 21005226 is about 275.9153016729.

Adding to 21005226 its reverse (62250012), we get a palindrome (83255238).

The spelling of 21005226 in words is "twenty-one million, five thousand, two hundred twenty-six".