21194878 has 4 divisors (see below), whose sum is σ = 31792320. Its totient is φ = 10597438.

The previous prime is 21194863. The next prime is 21194879. The reversal of 21194878 is 87849112.

It is a happy number.

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

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21194878.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21194879) by changing a digit.

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 as a sum of consecutive naturals, namely, 5298718 + ... + 5298721.

It is an arithmetic number, because the mean of its divisors is an integer number (7948080).

Almost surely, 2^21194878 is an apocalyptic number.

21194878 is a deficient number, since it is larger than the sum of its proper divisors (10597442).

21194878 is a wasteful number, since it uses less digits than its factorization.

21194878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10597441.

The product of its digits is 32256, while the sum is 40.

The square root of 21194878 is about 4603.7895260318. The cubic root of 21194878 is about 276.7432097371.

The spelling of 21194878 in words is "twenty-one million, one hundred ninety-four thousand, eight hundred seventy-eight".