866721878 has 16 divisors (see below), whose sum is σ = 1452865680. Its totient is φ = 384355200.

The previous prime is 866721799. The next prime is 866721899. The reversal of 866721878 is 878127668.

It is a happy 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, 479543 + ... + 481346.

It is an arithmetic number, because the mean of its divisors is an integer number (90804105).

Almost surely, 2^866721878 is an apocalyptic number.

866721878 is a deficient number, since it is larger than the sum of its proper divisors (586143802).

866721878 is a wasteful number, since it uses less digits than its factorization.

866721878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 960943.

The product of its digits is 1806336, while the sum is 53.

The square root of 866721878 is about 29440.1405906969. The cubic root of 866721878 is about 953.4397475499.

The spelling of 866721878 in words is "eight hundred sixty-six million, seven hundred twenty-one thousand, eight hundred seventy-eight".