21211285 has 16 divisors (see below), whose sum is σ = 26422272. Its totient is φ = 16329600.

The previous prime is 21211259. The next prime is 21211319. The reversal of 21211285 is 58211212.

It is not a de Polignac number, because 21211285 - 2⁹ = 21210773 is a prime.

It is a super-2 number, since 2×21211285² = 899837222702450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 43312 + ... + 43798.

It is an arithmetic number, because the mean of its divisors is an integer number (1651392).

Almost surely, 2^21211285 is an apocalyptic number.

It is an amenable number.

21211285 is a deficient number, since it is larger than the sum of its proper divisors (5210987).

21211285 is a wasteful number, since it uses less digits than its factorization.

21211285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 804.

The product of its digits is 320, while the sum is 22.

The square root of 21211285 is about 4605.5710829386. The cubic root of 21211285 is about 276.8146004875.

Adding to 21211285 its reverse (58211212), we get a palindrome (79422497).

The spelling of 21211285 in words is "twenty-one million, two hundred eleven thousand, two hundred eighty-five".