21057226 has 4 divisors (see below), whose sum is σ = 31585842. Its totient is φ = 10528612.

The previous prime is 21057209. The next prime is 21057241. The reversal of 21057226 is 62275012.

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

It can be written as a sum of positive squares in only one way, i.e., 19492225 + 1565001 = 4415^2 + 1251^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21057226.

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 as a sum of consecutive naturals, namely, 5264305 + ... + 5264308.

Almost surely, 2^21057226 is an apocalyptic number.

21057226 is a deficient number, since it is larger than the sum of its proper divisors (10528616).

21057226 is a wasteful number, since it uses less digits than its factorization.

21057226 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10528615.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21057226 is about 4588.8153155253. The cubic root of 21057226 is about 276.1427970024.

The spelling of 21057226 in words is "twenty-one million, fifty-seven thousand, two hundred twenty-six".