21045081 has 16 divisors (see below), whose sum is σ = 28880064. Its totient is φ = 13625664.

The previous prime is 21045077. The next prime is 21045083. The reversal of 21045081 is 18054012.

It is not a de Polignac number, because 21045081 - 2² = 21045077 is a prime.

It is a super-2 number, since 2×21045081² = 885790868593122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21045083) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16395 + ... + 17631.

It is an arithmetic number, because the mean of its divisors is an integer number (1805004).

Almost surely, 2^21045081 is an apocalyptic number.

It is an amenable number.

21045081 is a deficient number, since it is larger than the sum of its proper divisors (7834983).

21045081 is a wasteful number, since it uses less digits than its factorization.

21045081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1400.

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21045081 is about 4587.4917983578. The cubic root of 21045081 is about 276.0896972691.

Adding to 21045081 its reverse (18054012), we get a palindrome (39099093).

The spelling of 21045081 in words is "twenty-one million, forty-five thousand, eighty-one".