21235213 has 2 divisors, whose sum is σ = 21235214. Its totient is φ = 21235212.

The previous prime is 21235183. The next prime is 21235223. The reversal of 21235213 is 31253212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15069924 + 6165289 = 3882^2 + 2483^2 .

It is a cyclic number.

It is not a de Polignac number, because 21235213 - 2⁹ = 21234701 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21235223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10617606 + 10617607.

It is an arithmetic number, because the mean of its divisors is an integer number (10617607).

Almost surely, 2^21235213 is an apocalyptic number.

It is an amenable number.

21235213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21235213 is an equidigital number, since it uses as much as digits as its factorization.

21235213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 360, while the sum is 19.

The square root of 21235213 is about 4608.1680741917. The cubic root of 21235213 is about 276.9186509284.

Adding to 21235213 its reverse (31253212), we get a palindrome (52488425).

The spelling of 21235213 in words is "twenty-one million, two hundred thirty-five thousand, two hundred thirteen".