20816571878 has 4 divisors (see below), whose sum is σ = 31224857820. Its totient is φ = 10408285938.

The previous prime is 20816571821. The next prime is 20816571917. The reversal of 20816571878 is 87817561802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87817561802 = 2 ⋅43908780901.

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 (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5204142968 + ... + 5204142971.

It is an arithmetic number, because the mean of its divisors is an integer number (7806214455).

Almost surely, 2^20816571878 is an apocalyptic number.

20816571878 is a deficient number, since it is larger than the sum of its proper divisors (10408285942).

20816571878 is a wasteful number, since it uses less digits than its factorization.

20816571878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10408285941.

The product of its (nonzero) digits is 1505280, while the sum is 53.

The spelling of 20816571878 in words is "twenty billion, eight hundred sixteen million, five hundred seventy-one thousand, eight hundred seventy-eight".