21730413 has 4 divisors (see below), whose sum is σ = 28973888. Its totient is φ = 14486940.

The previous prime is 21730393. The next prime is 21730417. The reversal of 21730413 is 31403712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21730413 - 2¹² = 21726317 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21730413.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730417) 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 3 ways as a sum of consecutive naturals, for example, 3621733 + ... + 3621738.

It is an arithmetic number, because the mean of its divisors is an integer number (7243472).

Almost surely, 2^21730413 is an apocalyptic number.

It is an amenable number.

21730413 is a deficient number, since it is larger than the sum of its proper divisors (7243475).

21730413 is an equidigital number, since it uses as much as digits as its factorization.

21730413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7243474.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21730413 is about 4661.5891067317. The cubic root of 21730413 is about 279.0546905287.

The spelling of 21730413 in words is "twenty-one million, seven hundred thirty thousand, four hundred thirteen".