21730599 has 40 divisors (see below), whose sum is σ = 36677520. Its totient is φ = 12715920.

The previous prime is 21730559. The next prime is 21730637. The reversal of 21730599 is 99503712.

It is not a de Polignac number, because 21730599 - 2¹² = 21726503 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730519) 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 39 ways as a sum of consecutive naturals, for example, 749317 + ... + 749345.

It is an arithmetic number, because the mean of its divisors is an integer number (916938).

Almost surely, 2^21730599 is an apocalyptic number.

21730599 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21730599 is a deficient number, since it is larger than the sum of its proper divisors (14946921).

21730599 is an frugal number, since it uses more digits than its factorization.

21730599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110 (or 43 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 21730599 is about 4661.6090569673. The cubic root of 21730599 is about 279.0554867096.

The spelling of 21730599 in words is "twenty-one million, seven hundred thirty thousand, five hundred ninety-nine".