20851878 has 16 divisors (see below), whose sum is σ = 41751360. Its totient is φ = 6942696.

The previous prime is 20851867. The next prime is 20851891. The reversal of 20851878 is 87815802.

It is a super-2 number, since 2×20851878² = 869601632253768, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6513 + ... + 9171.

It is an arithmetic number, because the mean of its divisors is an integer number (2609460).

Almost surely, 2^20851878 is an apocalyptic number.

20851878 is an abundant number, since it is smaller than the sum of its proper divisors (20899482).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20851878 is a wasteful number, since it uses less digits than its factorization.

20851878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3971.

The product of its (nonzero) digits is 35840, while the sum is 39.

The square root of 20851878 is about 4566.3856604540. The cubic root of 20851878 is about 275.2422240484.

The spelling of 20851878 in words is "twenty million, eight hundred fifty-one thousand, eight hundred seventy-eight".