21947503 has 2 divisors, whose sum is σ = 21947504. Its totient is φ = 21947502.

The previous prime is 21947491. The next prime is 21947507. The reversal of 21947503 is 30574912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21947503 is a prime.

It is equal to p_1386184 and since 21947503 and 1386184 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21947507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10973751 + 10973752.

It is an arithmetic number, because the mean of its divisors is an integer number (10973752).

Almost surely, 2^21947503 is an apocalyptic number.

21947503 is a deficient number, since it is larger than the sum of its proper divisors (1).

21947503 is an equidigital number, since it uses as much as digits as its factorization.

21947503 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21947503 is about 4684.8162183804. The cubic root of 21947503 is about 279.9808787963.

The spelling of 21947503 in words is "twenty-one million, nine hundred forty-seven thousand, five hundred three".