21090163 has 4 divisors (see below), whose sum is σ = 21817440. Its totient is φ = 20362888.

The previous prime is 21090161. The next prime is 21090197. The reversal of 21090163 is 36109012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21090163 - 2¹ = 21090161 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21090161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 363595 + ... + 363652.

It is an arithmetic number, because the mean of its divisors is an integer number (5454360).

Almost surely, 2^21090163 is an apocalyptic number.

21090163 is a deficient number, since it is larger than the sum of its proper divisors (727277).

21090163 is an equidigital number, since it uses as much as digits as its factorization.

21090163 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727276.

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 21090163 is about 4592.4027480176. The cubic root of 21090163 is about 276.2866997372.

Adding to 21090163 its reverse (36109012), we get a palindrome (57199175).

The spelling of 21090163 in words is "twenty-one million, ninety thousand, one hundred sixty-three".