21450161 has 2 divisors, whose sum is σ = 21450162. Its totient is φ = 21450160.

The previous prime is 21450137. The next prime is 21450179. The reversal of 21450161 is 16105412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21390625 + 59536 = 4625^2 + 244^2 .

It is a cyclic number.

It is not a de Polignac number, because 21450161 - 2¹⁰ = 21449137 is a prime.

It is a Sophie Germain prime.

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

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21450181) 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, 10725080 + 10725081.

It is an arithmetic number, because the mean of its divisors is an integer number (10725081).

Almost surely, 2^21450161 is an apocalyptic number.

It is an amenable number.

21450161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21450161 is an equidigital number, since it uses as much as digits as its factorization.

21450161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21450161 is about 4631.4318520302. The cubic root of 21450161 is about 277.8498619975.

Adding to 21450161 its reverse (16105412), we get a palindrome (37555573).

The spelling of 21450161 in words is "twenty-one million, four hundred fifty thousand, one hundred sixty-one".