21221530 has 16 divisors (see below), whose sum is σ = 41671584. Its totient is φ = 7716880.

The previous prime is 21221521. The next prime is 21221531. The reversal of 21221530 is 3512212.

It is not an unprimeable number, because it can be changed into a prime (21221531) 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 7 ways as a sum of consecutive naturals, for example, 96352 + ... + 96571.

It is an arithmetic number, because the mean of its divisors is an integer number (2604474).

Almost surely, 2^21221530 is an apocalyptic number.

21221530 is a deficient number, since it is larger than the sum of its proper divisors (20450054).

21221530 is a wasteful number, since it uses less digits than its factorization.

21221530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192941.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21221530 is about 4606.6831885859. The cubic root of 21221530 is about 276.8591602446.

Adding to 21221530 its reverse (3512212), we get a palindrome (24733742).

The spelling of 21221530 in words is "twenty-one million, two hundred twenty-one thousand, five hundred thirty".