21279441 has 4 divisors (see below), whose sum is σ = 28372592. Its totient is φ = 14186292.

The previous prime is 21279431. The next prime is 21279443. The reversal of 21279441 is 14497212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21279441 - 2⁵ = 21279409 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21279399 and 21279408.

It is not an unprimeable number, because it can be changed into a prime (21279443) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3546571 + ... + 3546576.

It is an arithmetic number, because the mean of its divisors is an integer number (7093148).

Almost surely, 2^21279441 is an apocalyptic number.

It is an amenable number.

21279441 is a deficient number, since it is larger than the sum of its proper divisors (7093151).

21279441 is an equidigital number, since it uses as much as digits as its factorization.

21279441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7093150.

The product of its digits is 4032, while the sum is 30.

The square root of 21279441 is about 4612.9644481613. The cubic root of 21279441 is about 277.1107699492.

The spelling of 21279441 in words is "twenty-one million, two hundred seventy-nine thousand, four hundred forty-one".