21221053 has 4 divisors (see below), whose sum is σ = 24252640. Its totient is φ = 18189468.

The previous prime is 21221051. The next prime is 21221063. The reversal of 21221053 is 35012212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21221053 - 2¹ = 21221051 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1515783 + ... + 1515796.

It is an arithmetic number, because the mean of its divisors is an integer number (6063160).

Almost surely, 2^21221053 is an apocalyptic number.

It is an amenable number.

21221053 is a deficient number, since it is larger than the sum of its proper divisors (3031587).

21221053 is an equidigital number, since it uses as much as digits as its factorization.

21221053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3031586.

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

The square root of 21221053 is about 4606.6314156876. The cubic root of 21221053 is about 276.8570858919.

Adding to 21221053 its reverse (35012212), we get a palindrome (56233265).

The spelling of 21221053 in words is "twenty-one million, two hundred twenty-one thousand, fifty-three".