21272775 has 12 divisors (see below), whose sum is σ = 35171112. Its totient is φ = 11345440.

The previous prime is 21272759. The next prime is 21272803. The reversal of 21272775 is 57727212.

It is not a de Polignac number, because 21272775 - 2⁴ = 21272759 is a prime.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 141744 + ... + 141893.

It is an arithmetic number, because the mean of its divisors is an integer number (2930926).

Almost surely, 2^21272775 is an apocalyptic number.

21272775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21272775 is a deficient number, since it is larger than the sum of its proper divisors (13898337).

21272775 is a wasteful number, since it uses less digits than its factorization.

21272775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283650 (or 283645 counting only the distinct ones).

The product of its digits is 13720, while the sum is 33.

The square root of 21272775 is about 4612.2418626954. The cubic root of 21272775 is about 277.0818310105.

Adding to 21272775 its reverse (57727212), we get a palindrome (78999987).

It can be divided in two parts, 21 and 272775, that multiplied together give a palindrome (5728275).

The spelling of 21272775 in words is "twenty-one million, two hundred seventy-two thousand, seven hundred seventy-five".