21313285 has 12 divisors (see below), whose sum is σ = 29751948. Its totient is φ = 14614656.

The previous prime is 21313283. The next prime is 21313297. The reversal of 21313285 is 58231312.

It can be written as a sum of positive squares in 2 ways, for example, as 12545764 + 8767521 = 3542^2 + 2961^2 .

It is not a de Polignac number, because 21313285 - 2¹ = 21313283 is a prime.

It is a super-2 number, since 2×21313285² = 908512234982450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21313283) 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 11 ways as a sum of consecutive naturals, for example, 43252 + ... + 43741.

It is an arithmetic number, because the mean of its divisors is an integer number (2479329).

Almost surely, 2^21313285 is an apocalyptic number.

It is an amenable number.

21313285 is a deficient number, since it is larger than the sum of its proper divisors (8438663).

21313285 is an equidigital number, since it uses as much as digits as its factorization.

21313285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87012 (or 87005 counting only the distinct ones).

The product of its digits is 1440, while the sum is 25.

The square root of 21313285 is about 4616.6313476387. The cubic root of 21313285 is about 277.2576028984.

Adding to 21313285 its reverse (58231312), we get a palindrome (79544597).

The spelling of 21313285 in words is "twenty-one million, three hundred thirteen thousand, two hundred eighty-five".