820025855 has 32 divisors (see below), whose sum is σ = 1139158080. Its totient is φ = 560056320.

The previous prime is 820025819. The next prime is 820025879. The reversal of 820025855 is 558520028.

It is a Cunningham number, because it is equal to 936³-1.

It is a de Polignac number, because none of the positive numbers 2^k-820025855 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 662297 + ... + 663533.

It is an arithmetic number, because the mean of its divisors is an integer number (35598690).

Almost surely, 2^820025855 is an apocalyptic number.

820025855 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

820025855 is a deficient number, since it is larger than the sum of its proper divisors (319132225).

820025855 is a wasteful number, since it uses less digits than its factorization.

820025855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1979.

The product of its (nonzero) digits is 32000, while the sum is 35.

The square root of 820025855 is about 28636.0935708766. The cubic root of 820025855 is about 935.9999996195. Note that the first 6 decimals are identical.

The spelling of 820025855 in words is "eight hundred twenty million, twenty-five thousand, eight hundred fifty-five".