21431344 has 40 divisors (see below), whose sum is σ = 45568512. Its totient is φ = 9683520.

The previous prime is 21431341. The next prime is 21431353. The reversal of 21431344 is 44313412.

21431344 = T₂₆₅ + T₂₆₆ + ... + T₅₂₇.

It is a super-4 number, since 4×21431344⁴ (a number of 30 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (21431341) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46057 + ... + 46519.

Almost surely, 2^21431344 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 21431344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22784256).

21431344 is an abundant number, since it is smaller than the sum of its proper divisors (24137168).

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

21431344 is a wasteful number, since it uses less digits than its factorization.

21431344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 745 (or 739 counting only the distinct ones).

The product of its digits is 1152, while the sum is 22.

The square root of 21431344 is about 4629.3999611181. The cubic root of 21431344 is about 277.7685909614.

Adding to 21431344 its reverse (44313412), we get a palindrome (65744756).

The spelling of 21431344 in words is "twenty-one million, four hundred thirty-one thousand, three hundred forty-four".