21160081 has 2 divisors, whose sum is σ = 21160082. Its totient is φ = 21160080.

The previous prime is 21160079. The next prime is 21160123. The reversal of 21160081 is 18006112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21160000 + 81 = 4600^2 + 9^2 .

It is a cyclic number.

It is not a de Polignac number, because 21160081 - 2¹ = 21160079 is a prime.

It is a super-2 number, since 2×21160081² = 895498055853122, which contains 22 as substring.

Together with 21160079, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21160001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10580040 + 10580041.

It is an arithmetic number, because the mean of its divisors is an integer number (10580041).

Almost surely, 2^21160081 is an apocalyptic number.

It is an amenable number.

21160081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21160081 is an equidigital number, since it uses as much as digits as its factorization.

21160081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 19.

The square root of 21160081 is about 4600.0088043394. The cubic root of 21160081 is about 276.5916777136.

Adding to 21160081 its reverse (18006112), we get a palindrome (39166193).

It can be divided in two parts, 211600 and 81, that multiplied together give a square (17139600 = 4140²).

The spelling of 21160081 in words is "twenty-one million, one hundred sixty thousand, eighty-one".