21068399 has 10 divisors (see below), whose sum is σ = 23191200. Its totient is φ = 19139780.

The previous prime is 21068357. The next prime is 21068417. The reversal of 21068399 is 99386012.

It is a de Polignac number, because none of the positive numbers 2^k-21068399 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 (21068309) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 13922 + ... + 15360.

It is an arithmetic number, because the mean of its divisors is an integer number (2319120).

Almost surely, 2^21068399 is an apocalyptic number.

21068399 is a deficient number, since it is larger than the sum of its proper divisors (2122801).

21068399 is an frugal number, since it uses more digits than its factorization.

21068399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1483 (or 1450 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21068399 is about 4590.0325706905. The cubic root of 21068399 is about 276.1916289795.

The spelling of 21068399 in words is "twenty-one million, sixty-eight thousand, three hundred ninety-nine".