21561167 has 2 divisors, whose sum is σ = 21561168. Its totient is φ = 21561166.

The previous prime is 21561131. The next prime is 21561173. The reversal of 21561167 is 76116512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21561167 - 2⁸ = 21560911 is a prime.

It is a super-3 number, since 3×21561167³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21561107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10780583 + 10780584.

It is an arithmetic number, because the mean of its divisors is an integer number (10780584).

Almost surely, 2^21561167 is an apocalyptic number.

21561167 is a deficient number, since it is larger than the sum of its proper divisors (1).

21561167 is an equidigital number, since it uses as much as digits as its factorization.

21561167 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 29.

The square root of 21561167 is about 4643.4003704182. The cubic root of 21561167 is about 278.3283346977.

Adding to 21561167 its reverse (76116512), we get a palindrome (97677679).

The spelling of 21561167 in words is "twenty-one million, five hundred sixty-one thousand, one hundred sixty-seven".