820857157 has 4 divisors (see below), whose sum is σ = 821084076. Its totient is φ = 820630240.

The previous prime is 820857137. The next prime is 820857181. The reversal of 820857157 is 751758028.

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 416404836 + 404452321 = 20406^2 + 20111^2 .

It is a cyclic number.

It is not a de Polignac number, because 820857157 - 2¹⁹ = 820332869 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 (820857127) 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, 107944 + ... + 115297.

It is an arithmetic number, because the mean of its divisors is an integer number (205271019).

Almost surely, 2^820857157 is an apocalyptic number.

It is an amenable number.

820857157 is a deficient number, since it is larger than the sum of its proper divisors (226919).

820857157 is a wasteful number, since it uses less digits than its factorization.

820857157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226918.

The product of its (nonzero) digits is 156800, while the sum is 43.

The square root of 820857157 is about 28650.6048278217. The cubic root of 820857157 is about 936.3161831001.

The spelling of 820857157 in words is "eight hundred twenty million, eight hundred fifty-seven thousand, one hundred fifty-seven".