21024161 has 4 divisors (see below), whose sum is σ = 21052692. Its totient is φ = 20995632.

The previous prime is 21024137. The next prime is 21024173. The reversal of 21024161 is 16142012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13184161 + 7840000 = 3631^2 + 2800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21024161 - 2⁶ = 21024097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21024361) 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, 13130 + ... + 14643.

It is an arithmetic number, because the mean of its divisors is an integer number (5263173).

Almost surely, 2^21024161 is an apocalyptic number.

It is an amenable number.

21024161 is a deficient number, since it is larger than the sum of its proper divisors (28531).

21024161 is an equidigital number, since it uses as much as digits as its factorization.

21024161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28530.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21024161 is about 4585.2111183674. The cubic root of 21024161 is about 275.9981840180.

Adding to 21024161 its reverse (16142012), we get a palindrome (37166173).

The spelling of 21024161 in words is "twenty-one million, twenty-four thousand, one hundred sixty-one".