821138441 has 4 divisors (see below), whose sum is σ = 821243412. Its totient is φ = 821033472.

The previous prime is 821138431. The next prime is 821138467. The reversal of 821138441 is 144831128.

It is a happy number.

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 724686400 + 96452041 = 26920^2 + 9821^2 .

It is a cyclic number.

It is not a de Polignac number, because 821138441 - 2⁶ = 821138377 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 821138398 and 821138407.

It is not an unprimeable number, because it can be changed into a prime (821138431) 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, 39716 + ... + 56741.

It is an arithmetic number, because the mean of its divisors is an integer number (205310853).

Almost surely, 2^821138441 is an apocalyptic number.

It is an amenable number.

821138441 is a deficient number, since it is larger than the sum of its proper divisors (104971).

821138441 is an equidigital number, since it uses as much as digits as its factorization.

821138441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104970.

The product of its digits is 6144, while the sum is 32.

The square root of 821138441 is about 28655.5132740630. The cubic root of 821138441 is about 936.4231203756.

Adding to 821138441 its reverse (144831128), we get a palindrome (965969569).

The spelling of 821138441 in words is "eight hundred twenty-one million, one hundred thirty-eight thousand, four hundred forty-one".