21703687 has 12 divisors (see below), whose sum is σ = 22764456. Its totient is φ = 20689760.

The previous prime is 21703667. The next prime is 21703699. The reversal of 21703687 is 78630712.

It is a de Polignac number, because none of the positive numbers 2^k-21703687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21703607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 110073 + ... + 110269.

It is an arithmetic number, because the mean of its divisors is an integer number (1897038).

Almost surely, 2^21703687 is an apocalyptic number.

21703687 is a deficient number, since it is larger than the sum of its proper divisors (1060769).

21703687 is a wasteful number, since it uses less digits than its factorization.

21703687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386 (or 357 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 21703687 is about 4658.7216057627. The cubic root of 21703687 is about 278.9402414804.

Subtracting 21703687 from its reverse (78630712), we obtain a square (56927025 = 7545²).

The spelling of 21703687 in words is "twenty-one million, seven hundred three thousand, six hundred eighty-seven".