21151312 has 80 divisors (see below), whose sum is σ = 51385600. Its totient is φ = 8211456.

The previous prime is 21151307. The next prime is 21151343. The reversal of 21151312 is 21315112.

It is a Harshad number since it is a multiple of its sum of digits (16).

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, 106189 + ... + 106387.

It is an arithmetic number, because the mean of its divisors is an integer number (642320).

Almost surely, 2^21151312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21151312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25692800).

21151312 is an abundant number, since it is smaller than the sum of its proper divisors (30234288).

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

21151312 is a wasteful number, since it uses less digits than its factorization.

21151312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300 (or 294 counting only the distinct ones).

The product of its digits is 60, while the sum is 16.

The square root of 21151312 is about 4599.0555552200. The cubic root of 21151312 is about 276.5534647606.

Adding to 21151312 its reverse (21315112), we get a palindrome (42466424).

The spelling of 21151312 in words is "twenty-one million, one hundred fifty-one thousand, three hundred twelve".