21730716 has 108 divisors (see below), whose sum is σ = 65065728. Its totient is φ = 6096384.

The previous prime is 21730693. The next prime is 21730727. The reversal of 21730716 is 61703712.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 21730716.

It is a congruent number.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 171045 + ... + 171171.

Almost surely, 2^21730716 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21730716, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32532864).

21730716 is an abundant number, since it is smaller than the sum of its proper divisors (43335012).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21730716 is a wasteful number, since it uses less digits than its factorization.

21730716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248 (or 236 counting only the distinct ones).

The product of its (nonzero) digits is 1764, while the sum is 27.

The square root of 21730716 is about 4661.6216062654. The cubic root of 21730716 is about 279.0559875308.

The spelling of 21730716 in words is "twenty-one million, seven hundred thirty thousand, seven hundred sixteen".