21032161 has 2 divisors, whose sum is σ = 21032162. Its totient is φ = 21032160.

The previous prime is 21032159. The next prime is 21032197. The reversal of 21032161 is 16123012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12737761 + 8294400 = 3569^2 + 2880^2 .

It is a cyclic number.

It is not a de Polignac number, because 21032161 - 2¹ = 21032159 is a prime.

Together with 21032159, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21033161) 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, 10516080 + 10516081.

It is an arithmetic number, because the mean of its divisors is an integer number (10516081).

Almost surely, 2^21032161 is an apocalyptic number.

It is an amenable number.

21032161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21032161 is an equidigital number, since it uses as much as digits as its factorization.

21032161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21032161 is about 4586.0834052599. The cubic root of 21032161 is about 276.0331866906.

Adding to 21032161 its reverse (16123012), we get a palindrome (37155173).

The spelling of 21032161 in words is "twenty-one million, thirty-two thousand, one hundred sixty-one".