21521266 has 8 divisors (see below), whose sum is σ = 34765164. Its totient is φ = 9932880.

The previous prime is 21521263. The next prime is 21521299. The reversal of 21521266 is 66212512.

It can be written as a sum of positive squares in 2 ways, for example, as 19053225 + 2468041 = 4365^2 + 1571^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 21521266.

It is not an unprimeable number, because it can be changed into a prime (21521263) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 413845 + ... + 413896.

Almost surely, 2^21521266 is an apocalyptic number.

21521266 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21521266 is a deficient number, since it is larger than the sum of its proper divisors (13243898).

21521266 is a wasteful number, since it uses less digits than its factorization.

21521266 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 827756.

The product of its digits is 1440, while the sum is 25.

The square root of 21521266 is about 4639.1018527297. The cubic root of 21521266 is about 278.1565376180.

Adding to 21521266 its reverse (66212512), we get a palindrome (87733778).

The spelling of 21521266 in words is "twenty-one million, five hundred twenty-one thousand, two hundred sixty-six".