21247803 has 12 divisors (see below), whose sum is σ = 31681728. Its totient is φ = 13708080.

The previous prime is 21247789. The next prime is 21247819. The reversal of 21247803 is 30874212.

It is not a de Polignac number, because 21247803 - 2¹² = 21243707 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21247823) 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, 37800 + ... + 38357.

It is an arithmetic number, because the mean of its divisors is an integer number (2640144).

Almost surely, 2^21247803 is an apocalyptic number.

21247803 is a deficient number, since it is larger than the sum of its proper divisors (10433925).

21247803 is a wasteful number, since it uses less digits than its factorization.

21247803 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76194 (or 76191 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21247803 is about 4609.5339243789. The cubic root of 21247803 is about 276.9733669172.

The spelling of 21247803 in words is "twenty-one million, two hundred forty-seven thousand, eight hundred three".