21161121 has 8 divisors (see below), whose sum is σ = 28437504. Its totient is φ = 13996080.

The previous prime is 21161113. The next prime is 21161131. The reversal of 21161121 is 12116112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21161121 - 2³ = 21161113 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21161121.

It is not an unprimeable number, because it can be changed into a prime (21161131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27390 + ... + 28151.

It is an arithmetic number, because the mean of its divisors is an integer number (3554688).

Almost surely, 2^21161121 is an apocalyptic number.

It is an amenable number.

21161121 is a deficient number, since it is larger than the sum of its proper divisors (7276383).

21161121 is a wasteful number, since it uses less digits than its factorization.

21161121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55671.

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

The square root of 21161121 is about 4600.1218462123. The cubic root of 21161121 is about 276.5962090547.

Adding to 21161121 its reverse (12116112), we get a palindrome (33277233).

The spelling of 21161121 in words is "twenty-one million, one hundred sixty-one thousand, one hundred twenty-one".