821247853 has 4 divisors (see below), whose sum is σ = 823359420. Its totient is φ = 819136288.

The previous prime is 821247851. The next prime is 821247907. The reversal of 821247853 is 358742128.

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 571544649 + 249703204 = 23907^2 + 15802^2 .

It is a cyclic number.

It is not a de Polignac number, because 821247853 - 2¹ = 821247851 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821247851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1055200 + ... + 1055977.

It is an arithmetic number, because the mean of its divisors is an integer number (205839855).

Almost surely, 2^821247853 is an apocalyptic number.

It is an amenable number.

821247853 is a deficient number, since it is larger than the sum of its proper divisors (2111567).

821247853 is a wasteful number, since it uses less digits than its factorization.

821247853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2111566.

The product of its digits is 107520, while the sum is 40.

The square root of 821247853 is about 28657.4223020843. The cubic root of 821247853 is about 936.4647095364.

It can be divided in two parts, 8212 and 47853, that added together give a palindrome (56065).

The spelling of 821247853 in words is "eight hundred twenty-one million, two hundred forty-seven thousand, eight hundred fifty-three".