21389213 has 8 divisors (see below), whose sum is σ = 22828032. Its totient is φ = 19970496.

The previous prime is 21389177. The next prime is 21389239. The reversal of 21389213 is 31298312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21389213 - 2⁸ = 21388957 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 (21389713) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2795 + ... + 7112.

It is an arithmetic number, because the mean of its divisors is an integer number (2853504).

Almost surely, 2^21389213 is an apocalyptic number.

It is an amenable number.

21389213 is a deficient number, since it is larger than the sum of its proper divisors (1438819).

21389213 is a wasteful number, since it uses less digits than its factorization.

21389213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10051.

The product of its digits is 2592, while the sum is 29.

The square root of 21389213 is about 4624.8473488322. The cubic root of 21389213 is about 277.5864535976.

Subtracting 21389213 from its reverse (31298312), we obtain a palindrome (9909099).

The spelling of 21389213 in words is "twenty-one million, three hundred eighty-nine thousand, two hundred thirteen".