21279619 has 4 divisors (see below), whose sum is σ = 21355096. Its totient is φ = 21204144.

The previous prime is 21279613. The next prime is 21279637. The reversal of 21279619 is 91697212.

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 21279619 - 2³ = 21279611 is a prime.

It is a super-2 number, since 2×21279619² = 905644369570322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21279611) 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, 37314 + ... + 37879.

It is an arithmetic number, because the mean of its divisors is an integer number (5338774).

Almost surely, 2^21279619 is an apocalyptic number.

21279619 is a deficient number, since it is larger than the sum of its proper divisors (75477).

21279619 is an equidigital number, since it uses as much as digits as its factorization.

21279619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75476.

The product of its digits is 13608, while the sum is 37.

The square root of 21279619 is about 4612.9837415712. The cubic root of 21279619 is about 277.1115426132. Note that the first 3 decimals are identical.

The spelling of 21279619 in words is "twenty-one million, two hundred seventy-nine thousand, six hundred nineteen".