21231424 has 28 divisors (see below), whose sum is σ = 42419524. Its totient is φ = 10543104.

The previous prime is 21231421. The next prime is 21231433. The reversal of 21231424 is 42413212.

21231424 = T₃₇₁ + T₃₇₂ + ... + T₅₆₂.

It can be written as a sum of positive squares in 2 ways, for example, as 1871424 + 19360000 = 1368^2 + 4400^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8992 + ... + 11104.

It is an arithmetic number, because the mean of its divisors is an integer number (1514983).

Almost surely, 2^21231424 is an apocalyptic number.

It is an amenable number.

21231424 is a deficient number, since it is larger than the sum of its proper divisors (21188100).

21231424 is a wasteful number, since it uses less digits than its factorization.

21231424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2282 (or 2272 counting only the distinct ones).

The product of its digits is 384, while the sum is 19.

The square root of 21231424 is about 4607.7569380339. The cubic root of 21231424 is about 276.9021797463.

Adding to 21231424 its reverse (42413212), we get a palindrome (63644636).

The spelling of 21231424 in words is "twenty-one million, two hundred thirty-one thousand, four hundred twenty-four".