21298213 has 4 divisors (see below), whose sum is σ = 21367008. Its totient is φ = 21229420.

The previous prime is 21298187. The next prime is 21298217. The reversal of 21298213 is 31289212.

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 21298213 - 2⁵ = 21298181 is a prime.

It is a super-2 number, since 2×21298213² = 907227753986738, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21298217) 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, 33931 + ... + 34552.

It is an arithmetic number, because the mean of its divisors is an integer number (5341752).

Almost surely, 2^21298213 is an apocalyptic number.

It is an amenable number.

21298213 is a deficient number, since it is larger than the sum of its proper divisors (68795).

21298213 is an equidigital number, since it uses as much as digits as its factorization.

21298213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68794.

The product of its digits is 1728, while the sum is 28.

The square root of 21298213 is about 4614.9986998915. The cubic root of 21298213 is about 277.1922319022.

Subtracting 21298213 from its reverse (31289212), we obtain a palindrome (9990999).

The spelling of 21298213 in words is "twenty-one million, two hundred ninety-eight thousand, two hundred thirteen".