21394213 has 2 divisors, whose sum is σ = 21394214. Its totient is φ = 21394212.

The previous prime is 21394201. The next prime is 21394229. The reversal of 21394213 is 31249312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21362884 + 31329 = 4622^2 + 177^2 .

It is a cyclic number.

It is not a de Polignac number, because 21394213 - 2⁵ = 21394181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21394613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697106 + 10697107.

It is an arithmetic number, because the mean of its divisors is an integer number (10697107).

Almost surely, 2^21394213 is an apocalyptic number.

It is an amenable number.

21394213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21394213 is an equidigital number, since it uses as much as digits as its factorization.

21394213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1296, while the sum is 25.

The square root of 21394213 is about 4625.3878756273. The cubic root of 21394213 is about 277.6080816980.

The spelling of 21394213 in words is "twenty-one million, three hundred ninety-four thousand, two hundred thirteen".