21121312 has 24 divisors (see below), whose sum is σ = 43772400. Its totient is φ = 10004544.

The previous prime is 21121277. The next prime is 21121319. The reversal of 21121312 is 21312112.

21121312 is nontrivially palindromic in base 14.

It is a super-2 number, since 2×21121312² = 892219641202688, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121292 and 21121301.

It is not an unprimeable number, because it can be changed into a prime (21121319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16762 + ... + 17977.

It is an arithmetic number, because the mean of its divisors is an integer number (1823850).

Almost surely, 2^21121312 is an apocalyptic number.

It is an amenable number.

21121312 is an abundant number, since it is smaller than the sum of its proper divisors (22651088).

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

21121312 is a wasteful number, since it uses less digits than its factorization.

21121312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34768 (or 34760 counting only the distinct ones).

The product of its digits is 24, while the sum is 13.

The square root of 21121312 is about 4595.7928586915. The cubic root of 21121312 is about 276.4226528668.

Adding to 21121312 its reverse (21312112), we get a palindrome (42433424).

The spelling of 21121312 in words is "twenty-one million, one hundred twenty-one thousand, three hundred twelve".