21672271 has 2 divisors, whose sum is σ = 21672272. Its totient is φ = 21672270.

The previous prime is 21672239. The next prime is 21672319. The reversal of 21672271 is 17227612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21672271 - 2⁵ = 21672239 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21672221) 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 as a sum of consecutive naturals, namely, 10836135 + 10836136.

It is an arithmetic number, because the mean of its divisors is an integer number (10836136).

Almost surely, 2^21672271 is an apocalyptic number.

21672271 is a deficient number, since it is larger than the sum of its proper divisors (1).

21672271 is an equidigital number, since it uses as much as digits as its factorization.

21672271 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2352, while the sum is 28.

The square root of 21672271 is about 4655.3486443015. The cubic root of 21672271 is about 278.8055881953.

Adding to 21672271 its reverse (17227612), we get a palindrome (38899883).

The spelling of 21672271 in words is "twenty-one million, six hundred seventy-two thousand, two hundred seventy-one".