21121161 has 4 divisors (see below), whose sum is σ = 28161552. Its totient is φ = 14080772.

The previous prime is 21121129. The next prime is 21121171. The reversal of 21121161 is 16112112.

It is a happy number.

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 21121161 - 2⁵ = 21121129 is a prime.

It is a super-2 number, since 2×21121161² = 892206883975842, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121161.

It is not an unprimeable number, because it can be changed into a prime (21121171) 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, 3520191 + ... + 3520196.

It is an arithmetic number, because the mean of its divisors is an integer number (7040388).

Almost surely, 2^21121161 is an apocalyptic number.

It is an amenable number.

21121161 is a deficient number, since it is larger than the sum of its proper divisors (7040391).

21121161 is an equidigital number, since it uses as much as digits as its factorization.

21121161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7040390.

The product of its digits is 24, while the sum is 15.

The square root of 21121161 is about 4595.7764305936. The cubic root of 21121161 is about 276.4219941338.

Adding to 21121161 its reverse (16112112), we get a palindrome (37233273).

The spelling of 21121161 in words is "twenty-one million, one hundred twenty-one thousand, one hundred sixty-one".