855417821 has 4 divisors (see below), whose sum is σ = 859153500. Its totient is φ = 851682144.

The previous prime is 855417811. The next prime is 855417833. The reversal of 855417821 is 128714558.

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 388641796 + 466776025 = 19714^2 + 21605^2 .

It is not a de Polignac number, because 855417821 - 2¹⁰ = 855416797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (855417811) 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, 1867496 + ... + 1867953.

It is an arithmetic number, because the mean of its divisors is an integer number (214788375).

Almost surely, 2^855417821 is an apocalyptic number.

It is an amenable number.

855417821 is a deficient number, since it is larger than the sum of its proper divisors (3735679).

855417821 is a wasteful number, since it uses less digits than its factorization.

855417821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3735678.

The product of its digits is 89600, while the sum is 41.

The square root of 855417821 is about 29247.5267501374. The cubic root of 855417821 is about 949.2765761232.

The spelling of 855417821 in words is "eight hundred fifty-five million, four hundred seventeen thousand, eight hundred twenty-one".