21653161 has 4 divisors (see below), whose sum is σ = 21744000. Its totient is φ = 21562324.

The previous prime is 21653153. The next prime is 21653167. The reversal of 21653161 is 16135612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21653161 - 2³ = 21653153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21653167) 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, 45061 + ... + 45538.

It is an arithmetic number, because the mean of its divisors is an integer number (5436000).

Almost surely, 2^21653161 is an apocalyptic number.

It is an amenable number.

21653161 is a deficient number, since it is larger than the sum of its proper divisors (90839).

21653161 is an equidigital number, since it uses as much as digits as its factorization.

21653161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90838.

The product of its digits is 1080, while the sum is 25.

The square root of 21653161 is about 4653.2957137925. The cubic root of 21653161 is about 278.7236164509.

Adding to 21653161 its reverse (16135612), we get a palindrome (37788773).

The spelling of 21653161 in words is "twenty-one million, six hundred fifty-three thousand, one hundred sixty-one".