21439312 has 60 divisors (see below), whose sum is σ = 46286100. Its totient is φ = 9585664.

The previous prime is 21439307. The next prime is 21439343. The reversal of 21439312 is 21393412.

It can be written as a sum of positive squares in 2 ways, for example, as 9217296 + 12222016 = 3036^2 + 3496^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 143814 + ... + 143962.

It is an arithmetic number, because the mean of its divisors is an integer number (771435).

Almost surely, 2^21439312 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 21439312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23143050).

21439312 is an abundant number, since it is smaller than the sum of its proper divisors (24846788).

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

21439312 is a wasteful number, since it uses less digits than its factorization.

21439312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220 (or 191 counting only the distinct ones).

The product of its digits is 1296, while the sum is 25.

The square root of 21439312 is about 4630.2604678355. The cubic root of 21439312 is about 277.8030107330.

The spelling of 21439312 in words is "twenty-one million, four hundred thirty-nine thousand, three hundred twelve".