21246399 has 12 divisors (see below), whose sum is σ = 31519176. Its totient is φ = 13781232.

The previous prime is 21246367. The next prime is 21246403. The reversal of 21246399 is 99364212.

21246399 is a `hidden beast` number, since 2 + 12 + 4 + 639 + 9 = 666.

It is not a de Polignac number, because 21246399 - 2⁵ = 21246367 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21246499) 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 in 11 ways as a sum of consecutive naturals, for example, 31569 + ... + 32234.

It is an arithmetic number, because the mean of its divisors is an integer number (2626598).

Almost surely, 2^21246399 is an apocalyptic number.

21246399 is a deficient number, since it is larger than the sum of its proper divisors (10272777).

21246399 is a wasteful number, since it uses less digits than its factorization.

21246399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63846 (or 63843 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 21246399 is about 4609.3816288088. The cubic root of 21246399 is about 276.9672662210.

The spelling of 21246399 in words is "twenty-one million, two hundred forty-six thousand, three hundred ninety-nine".