21228197 has 8 divisors (see below), whose sum is σ = 21937344. Its totient is φ = 20528928.

The previous prime is 21228167. The next prime is 21228209. The reversal of 21228197 is 79182212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21228197 - 2⁶ = 21228133 is a prime.

It is a Duffinian number.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228167) 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 in 7 ways as a sum of consecutive naturals, for example, 2033 + ... + 6825.

It is an arithmetic number, because the mean of its divisors is an integer number (2742168).

Almost surely, 2^21228197 is an apocalyptic number.

It is an amenable number.

21228197 is a deficient number, since it is larger than the sum of its proper divisors (709147).

21228197 is a wasteful number, since it uses less digits than its factorization.

21228197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4939.

The product of its digits is 4032, while the sum is 32.

The square root of 21228197 is about 4607.4067543467. The cubic root of 21228197 is about 276.8881500921. Note that the first 3 decimals are identical.

The spelling of 21228197 in words is "twenty-one million, two hundred twenty-eight thousand, one hundred ninety-seven".