21211320 has 64 divisors (see below), whose sum is σ = 68533920. Its totient is φ = 5220864.

The previous prime is 21211319. The next prime is 21211339. The reversal of 21211320 is 2311212.

It is a super-2 number, since 2×21211320² = 899840192284800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21211296 and 21211305.

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, 5239 + ... + 8358.

Almost surely, 2^21211320 is an apocalyptic number.

21211320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211320 is an abundant number, since it is smaller than the sum of its proper divisors (47322600).

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

21211320 is a wasteful number, since it uses less digits than its factorization.

21211320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13624 (or 13620 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21211320 is about 4605.5748826829. The cubic root of 21211320 is about 276.8147527415.

Adding to 21211320 its reverse (2311212), we get a palindrome (23522532).

The spelling of 21211320 in words is "twenty-one million, two hundred eleven thousand, three hundred twenty".