21878854 has 4 divisors (see below), whose sum is σ = 32818284. Its totient is φ = 10939426.

The previous prime is 21878849. The next prime is 21878867. The reversal of 21878854 is 45887812.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21878854.

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, 5469712 + ... + 5469715.

It is an arithmetic number, because the mean of its divisors is an integer number (8204571).

Almost surely, 2^21878854 is an apocalyptic number.

21878854 is a deficient number, since it is larger than the sum of its proper divisors (10939430).

21878854 is a wasteful number, since it uses less digits than its factorization.

21878854 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10939429.

The product of its digits is 143360, while the sum is 43.

The square root of 21878854 is about 4677.4837252523. The cubic root of 21878854 is about 279.6886590404.

The spelling of 21878854 in words is "twenty-one million, eight hundred seventy-eight thousand, eight hundred fifty-four".