21139213 has 2 divisors, whose sum is σ = 21139214. Its totient is φ = 21139212.

The previous prime is 21139207. The next prime is 21139243. The reversal of 21139213 is 31293112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18636489 + 2502724 = 4317^2 + 1582^2 .

It is a cyclic number.

It is not a de Polignac number, because 21139213 - 2²¹ = 19042061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21139243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10569606 + 10569607.

It is an arithmetic number, because the mean of its divisors is an integer number (10569607).

Almost surely, 2^21139213 is an apocalyptic number.

It is an amenable number.

21139213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21139213 is an equidigital number, since it uses as much as digits as its factorization.

21139213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 324, while the sum is 22.

The square root of 21139213 is about 4597.7399882986. The cubic root of 21139213 is about 276.5007232164.

The spelling of 21139213 in words is "twenty-one million, one hundred thirty-nine thousand, two hundred thirteen".