21271919 has 4 divisors (see below), whose sum is σ = 21632520. Its totient is φ = 20911320.

The previous prime is 21271903. The next prime is 21271931. The reversal of 21271919 is 91917212.

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 21271919 - 2⁴ = 21271903 is a prime.

It is a super-2 number, since 2×21271919² = 904989075885122, 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 (21271949) 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 3 ways as a sum of consecutive naturals, for example, 180212 + ... + 180329.

It is an arithmetic number, because the mean of its divisors is an integer number (5408130).

Almost surely, 2^21271919 is an apocalyptic number.

21271919 is a deficient number, since it is larger than the sum of its proper divisors (360601).

21271919 is an equidigital number, since it uses as much as digits as its factorization.

21271919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360600.

The product of its digits is 2268, while the sum is 32.

The square root of 21271919 is about 4612.1490652406. The cubic root of 21271919 is about 277.0781144412.

The spelling of 21271919 in words is "twenty-one million, two hundred seventy-one thousand, nine hundred nineteen".