21395393 has 2 divisors, whose sum is σ = 21395394. Its totient is φ = 21395392.

The previous prime is 21395383. The next prime is 21395419. The reversal of 21395393 is 39359312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18939904 + 2455489 = 4352^2 + 1567^2 .

It is a cyclic number.

It is not a de Polignac number, because 21395393 - 2⁶ = 21395329 is a prime.

It is not a weakly prime, because it can be changed into another prime (21395303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697696 + 10697697.

It is an arithmetic number, because the mean of its divisors is an integer number (10697697).

Almost surely, 2^21395393 is an apocalyptic number.

It is an amenable number.

21395393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21395393 is an equidigital number, since it uses as much as digits as its factorization.

21395393 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21870, while the sum is 35.

The square root of 21395393 is about 4625.5154307385. The cubic root of 21395393 is about 277.6131854381.

The spelling of 21395393 in words is "twenty-one million, three hundred ninety-five thousand, three hundred ninety-three".