21438619 has 4 divisors (see below), whose sum is σ = 21448096. Its totient is φ = 21429144.

The previous prime is 21438617. The next prime is 21438623. The reversal of 21438619 is 91683412.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21438619 - 2¹ = 21438617 is a prime.

It is a super-2 number, since 2×21438619² = 919228769254322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21438611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 862 + ... + 6604.

It is an arithmetic number, because the mean of its divisors is an integer number (5362024).

Almost surely, 2^21438619 is an apocalyptic number.

21438619 is a deficient number, since it is larger than the sum of its proper divisors (9477).

21438619 is an equidigital number, since it uses as much as digits as its factorization.

21438619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9476.

The product of its digits is 10368, while the sum is 34.

The square root of 21438619 is about 4630.1856334277. The cubic root of 21438619 is about 277.8000174846.

The spelling of 21438619 in words is "twenty-one million, four hundred thirty-eight thousand, six hundred nineteen".