21299213 has 16 divisors (see below), whose sum is σ = 23814000. Its totient is φ = 18923520.

The previous prime is 21299167. The next prime is 21299221. The reversal of 21299213 is 31299212.

It can be written as a sum of positive squares in 8 ways, for example, as 6538249 + 14760964 = 2557^2 + 3842^2 .

It is a cyclic number.

It is not a de Polignac number, because 21299213 - 2⁶ = 21299149 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 (21299273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47213 + ... + 47661.

It is an arithmetic number, because the mean of its divisors is an integer number (1488375).

Almost surely, 2^21299213 is an apocalyptic number.

It is an amenable number.

21299213 is a deficient number, since it is larger than the sum of its proper divisors (2514787).

21299213 is a wasteful number, since it uses less digits than its factorization.

21299213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592.

The product of its digits is 1944, while the sum is 29.

The square root of 21299213 is about 4615.1070410122. The cubic root of 21299213 is about 277.1965701049.

Subtracting 21299213 from its reverse (31299212), we obtain a palindrome (9999999).

It can be divided in two parts, 212992 and 13, that multiplied together give a square (2768896 = 1664²).

The spelling of 21299213 in words is "twenty-one million, two hundred ninety-nine thousand, two hundred thirteen".