21228078 has 16 divisors (see below), whose sum is σ = 43492176. Its totient is φ = 6903360.

The previous prime is 21228059. The next prime is 21228089. The reversal of 21228078 is 87082212.

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, 42901 + ... + 43392.

It is an arithmetic number, because the mean of its divisors is an integer number (2718261).

Almost surely, 2^21228078 is an apocalyptic number.

21228078 is an abundant number, since it is smaller than the sum of its proper divisors (22264098).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21228078 is a wasteful number, since it uses less digits than its factorization.

21228078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86339.

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 21228078 is about 4607.3938403397. The cubic root of 21228078 is about 276.8876327024.

The spelling of 21228078 in words is "twenty-one million, two hundred twenty-eight thousand, seventy-eight".