21272279 has 4 divisors (see below), whose sum is σ = 24311184. Its totient is φ = 18233376.

The previous prime is 21272269. The next prime is 21272291. The reversal of 21272279 is 97227212.

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

It is not a de Polignac number, because 21272279 - 2⁸ = 21272023 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21272269) 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, 1519442 + ... + 1519455.

It is an arithmetic number, because the mean of its divisors is an integer number (6077796).

Almost surely, 2^21272279 is an apocalyptic number.

21272279 is a deficient number, since it is larger than the sum of its proper divisors (3038905).

21272279 is an equidigital number, since it uses as much as digits as its factorization.

21272279 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3038904.

The product of its digits is 7056, while the sum is 32.

The square root of 21272279 is about 4612.1880924351. The cubic root of 21272279 is about 277.0796774965.

The spelling of 21272279 in words is "twenty-one million, two hundred seventy-two thousand, two hundred seventy-nine".