21081061 has 2 divisors, whose sum is σ = 21081062. Its totient is φ = 21081060.

The previous prime is 21081043. The next prime is 21081101. The reversal of 21081061 is 16018012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14861025 + 6220036 = 3855^2 + 2494^2 .

It is a cyclic number.

It is not a de Polignac number, because 21081061 - 2⁵ = 21081029 is a prime.

It is a super-2 number, since 2×21081061² = 888822265771442, which contains 22 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 (21081161) 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, 10540530 + 10540531.

It is an arithmetic number, because the mean of its divisors is an integer number (10540531).

Almost surely, 2^21081061 is an apocalyptic number.

It is an amenable number.

21081061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21081061 is an equidigital number, since it uses as much as digits as its factorization.

21081061 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 21081061 is about 4591.4116565605. The cubic root of 21081061 is about 276.2469478175.

Adding to 21081061 its reverse (16018012), we get a palindrome (37099073).

The spelling of 21081061 in words is "twenty-one million, eighty-one thousand, sixty-one".