21356441 has 4 divisors (see below), whose sum is σ = 22092900. Its totient is φ = 20619984.

The previous prime is 21356431. The next prime is 21356453. The reversal of 21356441 is 14465312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14280841 + 7075600 = 3779^2 + 2660^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21356441 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21356441.

It is not an unprimeable number, because it can be changed into a prime (21356431) 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, 368186 + ... + 368243.

It is an arithmetic number, because the mean of its divisors is an integer number (5523225).

Almost surely, 2^21356441 is an apocalyptic number.

It is an amenable number.

21356441 is a deficient number, since it is larger than the sum of its proper divisors (736459).

21356441 is an equidigital number, since it uses as much as digits as its factorization.

21356441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 736458.

The product of its digits is 2880, while the sum is 26.

The square root of 21356441 is about 4621.3029547953. The cubic root of 21356441 is about 277.4446108643. Note that the first 3 decimals are identical.

The spelling of 21356441 in words is "twenty-one million, three hundred fifty-six thousand, four hundred forty-one".