21661027 has 2 divisors, whose sum is σ = 21661028. Its totient is φ = 21661026.

The previous prime is 21661001. The next prime is 21661037. The reversal of 21661027 is 72016612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21661027 - 2¹¹ = 21658979 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21660992 and 21661010.

It is not a weakly prime, because it can be changed into another prime (21661037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10830513 + 10830514.

It is an arithmetic number, because the mean of its divisors is an integer number (10830514).

Almost surely, 2^21661027 is an apocalyptic number.

21661027 is a deficient number, since it is larger than the sum of its proper divisors (1).

21661027 is an equidigital number, since it uses as much as digits as its factorization.

21661027 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21661027 is about 4654.1408444524. The cubic root of 21661027 is about 278.7573632487.

Adding to 21661027 its reverse (72016612), we get a palindrome (93677639).

The spelling of 21661027 in words is "twenty-one million, six hundred sixty-one thousand, twenty-seven".