21683393 has 2 divisors, whose sum is σ = 21683394. Its totient is φ = 21683392.

The previous prime is 21683377. The next prime is 21683419. The reversal of 21683393 is 39338612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12054784 + 9628609 = 3472^2 + 3103^2 .

It is a cyclic number.

It is not a de Polignac number, because 21683393 - 2⁴ = 21683377 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21683093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10841696 + 10841697.

It is an arithmetic number, because the mean of its divisors is an integer number (10841697).

Almost surely, 2^21683393 is an apocalyptic number.

It is an amenable number.

21683393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21683393 is an equidigital number, since it uses as much as digits as its factorization.

21683393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 35.

The square root of 21683393 is about 4656.5430310478. The cubic root of 21683393 is about 278.8532734834.

The spelling of 21683393 in words is "twenty-one million, six hundred eighty-three thousand, three hundred ninety-three".