21305683 has 8 divisors (see below), whose sum is σ = 24915968. Its totient is φ = 17837064.

The previous prime is 21305681. The next prime is 21305689. The reversal of 21305683 is 38650312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21305683 - 2¹ = 21305681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21305681) 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 7 ways as a sum of consecutive naturals, for example, 35091 + ... + 35692.

It is an arithmetic number, because the mean of its divisors is an integer number (3114496).

Almost surely, 2^21305683 is an apocalyptic number.

21305683 is a deficient number, since it is larger than the sum of its proper divisors (3610285).

21305683 is an equidigital number, since it uses as much as digits as its factorization.

21305683 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70833.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21305683 is about 4615.8079466113. The cubic root of 21305683 is about 277.2246349953.

Adding to 21305683 its reverse (38650312), we get a palindrome (59955995).

The spelling of 21305683 in words is "twenty-one million, three hundred five thousand, six hundred eighty-three".