221139878 has 4 divisors (see below), whose sum is σ = 331709820. Its totient is φ = 110569938.

The previous prime is 221139869. The next prime is 221139883. The reversal of 221139878 is 878931122.

221139878 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 878931122 = 2 ⋅439465561.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55284968 + ... + 55284971.

It is an arithmetic number, because the mean of its divisors is an integer number (82927455).

Almost surely, 2^221139878 is an apocalyptic number.

221139878 is a deficient number, since it is larger than the sum of its proper divisors (110569942).

221139878 is a wasteful number, since it uses less digits than its factorization.

221139878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110569941.

The product of its digits is 48384, while the sum is 41.

The square root of 221139878 is about 14870.7726093838. The cubic root of 221139878 is about 604.7218884306.

The spelling of 221139878 in words is "two hundred twenty-one million, one hundred thirty-nine thousand, eight hundred seventy-eight".