21311312 has 40 divisors (see below), whose sum is σ = 47422560. Its totient is φ = 9175680.

The previous prime is 21311261. The next prime is 21311347.

21311312 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×21311312² = 908344038322688, which contains 22 as substring.

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 7 ways as a sum of consecutive naturals, for example, 158 + ... + 6530.

It is an arithmetic number, because the mean of its divisors is an integer number (1185564).

Almost surely, 2^21311312 is an apocalyptic number.

21311312 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21311312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23711280).

21311312 is an abundant number, since it is smaller than the sum of its proper divisors (26111248).

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

21311312 is a wasteful number, since it uses less digits than its factorization.

21311312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6411 (or 6405 counting only the distinct ones).

The product of its digits is 36, while the sum is 14.

The square root of 21311312 is about 4616.4176587480. The cubic root of 21311312 is about 277.2490472623.

It can be divided in two parts, 2131 and 1312, that added together give a palindrome (3443).

The spelling of 21311312 in words is "twenty-one million, three hundred eleven thousand, three hundred twelve".