21748687 has 2 divisors, whose sum is σ = 21748688. Its totient is φ = 21748686.

The previous prime is 21748651. The next prime is 21748693. The reversal of 21748687 is 78684712.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21748687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21748607) 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, 10874343 + 10874344.

It is an arithmetic number, because the mean of its divisors is an integer number (10874344).

Almost surely, 2^21748687 is an apocalyptic number.

21748687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21748687 is an equidigital number, since it uses as much as digits as its factorization.

21748687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 150528, while the sum is 43.

The square root of 21748687 is about 4663.5487560440. The cubic root of 21748687 is about 279.1328914758.

The spelling of 21748687 in words is "twenty-one million, seven hundred forty-eight thousand, six hundred eighty-seven".