21021266 has 16 divisors (see below), whose sum is σ = 36443520. Its totient is φ = 8907360.

The previous prime is 21021263. The next prime is 21021293. The reversal of 21021266 is 66212012.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21021263) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7190 + ... + 9681.

It is an arithmetic number, because the mean of its divisors is an integer number (2277720).

Almost surely, 2^21021266 is an apocalyptic number.

21021266 is a deficient number, since it is larger than the sum of its proper divisors (15422254).

21021266 is a wasteful number, since it uses less digits than its factorization.

21021266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16969.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21021266 is about 4584.8954186546. The cubic root of 21021266 is about 275.9855152379.

Adding to 21021266 its reverse (66212012), we get a palindrome (87233278).

The spelling of 21021266 in words is "twenty-one million, twenty-one thousand, two hundred sixty-six".