21828019 has 4 divisors (see below), whose sum is σ = 22044240. Its totient is φ = 21611800.

The previous prime is 21827977. The next prime is 21828029. The reversal of 21828019 is 91082812.

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 21828019 - 2¹¹ = 21825971 is a prime.

It is a super-2 number, since 2×21828019² = 952924826928722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21828029) 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, 107959 + ... + 108160.

It is an arithmetic number, because the mean of its divisors is an integer number (5511060).

Almost surely, 2^21828019 is an apocalyptic number.

21828019 is a deficient number, since it is larger than the sum of its proper divisors (216221).

21828019 is a wasteful number, since it uses less digits than its factorization.

21828019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216220.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 21828019 is about 4672.0465537064. The cubic root of 21828019 is about 279.4718743933.

It can be divided in two parts, 2182 and 8019, that added together give a palindrome (10201).

The spelling of 21828019 in words is "twenty-one million, eight hundred twenty-eight thousand, nineteen".