21221013 has 8 divisors (see below), whose sum is σ = 30866976. Its totient is φ = 12861200.

The previous prime is 21221003. The next prime is 21221021. The reversal of 21221013 is 31012212.

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

It is not a de Polignac number, because 21221013 - 2⁸ = 21220757 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21221013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 321498 + ... + 321563.

It is an arithmetic number, because the mean of its divisors is an integer number (3858372).

Almost surely, 2^21221013 is an apocalyptic number.

It is an amenable number.

21221013 is a deficient number, since it is larger than the sum of its proper divisors (9645963).

21221013 is a wasteful number, since it uses less digits than its factorization.

21221013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643075.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21221013 is about 4606.6270741183. The cubic root of 21221013 is about 276.8569119406.

Adding to 21221013 its reverse (31012212), we get a palindrome (52233225).

The spelling of 21221013 in words is "twenty-one million, two hundred twenty-one thousand, thirteen".