21323161 has 2 divisors, whose sum is σ = 21323162. Its totient is φ = 21323160.

The previous prime is 21323153. The next prime is 21323167. The reversal of 21323161 is 16132312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19527561 + 1795600 = 4419^2 + 1340^2 .

It is a cyclic number.

It is not a de Polignac number, because 21323161 - 2³ = 21323153 is a prime.

It is equal to p_1349101 and since 21323161 and 1349101 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21323167) 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, 10661580 + 10661581.

It is an arithmetic number, because the mean of its divisors is an integer number (10661581).

Almost surely, 2^21323161 is an apocalyptic number.

It is an amenable number.

21323161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21323161 is an equidigital number, since it uses as much as digits as its factorization.

21323161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 216, while the sum is 19.

The square root of 21323161 is about 4617.7008348311. The cubic root of 21323161 is about 277.3004208444.

Adding to 21323161 its reverse (16132312), we get a palindrome (37455473).

The spelling of 21323161 in words is "twenty-one million, three hundred twenty-three thousand, one hundred sixty-one".