21986903 has 2 divisors, whose sum is σ = 21986904. Its totient is φ = 21986902.

The previous prime is 21986897. The next prime is 21986953. The reversal of 21986903 is 30968912.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21986903 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21986953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10993451 + 10993452.

It is an arithmetic number, because the mean of its divisors is an integer number (10993452).

Almost surely, 2^21986903 is an apocalyptic number.

21986903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21986903 is an equidigital number, since it uses as much as digits as its factorization.

21986903 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21986903 is about 4689.0194070829. The cubic root of 21986903 is about 280.1483185293.

Subtracting 21986903 from its reverse (30968912), we obtain a square (8982009 = 2997²).

The spelling of 21986903 in words is "twenty-one million, nine hundred eighty-six thousand, nine hundred three".