21730726 has 16 divisors (see below), whose sum is σ = 34676640. Its totient is φ = 10177920.

The previous prime is 21730693. The next prime is 21730727. The reversal of 21730726 is 62703712.

It is a junction number, because it is equal to n+sod(n) for n = 21730694 and 21730703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730727) 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 7 ways as a sum of consecutive naturals, for example, 6391 + ... + 9181.

It is an arithmetic number, because the mean of its divisors is an integer number (2167290).

Almost surely, 2^21730726 is an apocalyptic number.

21730726 is a deficient number, since it is larger than the sum of its proper divisors (12945914).

21730726 is a wasteful number, since it uses less digits than its factorization.

21730726 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3039.

The product of its (nonzero) digits is 3528, while the sum is 28.

The square root of 21730726 is about 4661.6226788534. The cubic root of 21730726 is about 279.0560303360.

The spelling of 21730726 in words is "twenty-one million, seven hundred thirty thousand, seven hundred twenty-six".