21161867 has 2 divisors, whose sum is σ = 21161868. Its totient is φ = 21161866.

The previous prime is 21161857. The next prime is 21161869. The reversal of 21161867 is 76816112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21161867 - 2¹⁴ = 21145483 is a prime.

It is a super-2 number, since 2×21161867² = 895649229851378, which contains 22 as substring.

Together with 21161869, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21161869) 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, 10580933 + 10580934.

It is an arithmetic number, because the mean of its divisors is an integer number (10580934).

Almost surely, 2^21161867 is an apocalyptic number.

21161867 is a deficient number, since it is larger than the sum of its proper divisors (1).

21161867 is an equidigital number, since it uses as much as digits as its factorization.

21161867 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4032, while the sum is 32.

The square root of 21161867 is about 4600.2029303064. The cubic root of 21161867 is about 276.5994593291.

Adding to 21161867 its reverse (76816112), we get a palindrome (97977979).

The spelling of 21161867 in words is "twenty-one million, one hundred sixty-one thousand, eight hundred sixty-seven".