21440331 has 12 divisors (see below), whose sum is σ = 33784920. Its totient is φ = 12994080.

The previous prime is 21440317. The next prime is 21440351. The reversal of 21440331 is 13304412.

It is not a de Polignac number, because 21440331 - 2⁷ = 21440203 is a prime.

It is a super-2 number, since 2×21440331² = 919375586779122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21440351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 108186 + ... + 108383.

It is an arithmetic number, because the mean of its divisors is an integer number (2815410).

Almost surely, 2^21440331 is an apocalyptic number.

21440331 is a deficient number, since it is larger than the sum of its proper divisors (12344589).

21440331 is a wasteful number, since it uses less digits than its factorization.

21440331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216586 (or 216583 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21440331 is about 4630.3705035342. The cubic root of 21440331 is about 277.8074119436.

Adding to 21440331 its reverse (13304412), we get a palindrome (34744743).

The spelling of 21440331 in words is "twenty-one million, four hundred forty thousand, three hundred thirty-one".