21032221 has 36 divisors (see below), whose sum is σ = 27363420. Its totient is φ = 16087680.

The previous prime is 21032201. The next prime is 21032237. The reversal of 21032221 is 12223012.

It can be written as a sum of positive squares in 2 ways, for example, as 5112121 + 15920100 = 2261^2 + 3990^2 .

It is not a de Polignac number, because 21032221 - 2²³ = 12643613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21032201) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 512961 + ... + 513001.

It is an arithmetic number, because the mean of its divisors is an integer number (760095).

Almost surely, 2^21032221 is an apocalyptic number.

It is an amenable number.

21032221 is a deficient number, since it is larger than the sum of its proper divisors (6331199).

21032221 is a wasteful number, since it uses less digits than its factorization.

21032221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21032221 is about 4586.0899467847. The cubic root of 21032221 is about 276.0334491772.

Adding to 21032221 its reverse (12223012), we get a palindrome (33255233).

The spelling of 21032221 in words is "twenty-one million, thirty-two thousand, two hundred twenty-one".