21228719 has 4 divisors (see below), whose sum is σ = 22346040. Its totient is φ = 20111400.

The previous prime is 21228709. The next prime is 21228737. The reversal of 21228719 is 91782212.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21228719 - 2⁴ = 21228703 is a prime.

It is a super-2 number, since 2×21228719² = 901317020761922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 558632 + ... + 558669.

It is an arithmetic number, because the mean of its divisors is an integer number (5586510).

Almost surely, 2^21228719 is an apocalyptic number.

21228719 is a deficient number, since it is larger than the sum of its proper divisors (1117321).

21228719 is a wasteful number, since it uses less digits than its factorization.

21228719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1117320.

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

The square root of 21228719 is about 4607.4634019165. The cubic root of 21228719 is about 276.8904196275.

The spelling of 21228719 in words is "twenty-one million, two hundred twenty-eight thousand, seven hundred nineteen".