21181065 has 16 divisors (see below), whose sum is σ = 35883648. Its totient is φ = 10631936.

The previous prime is 21181037. The next prime is 21181073. The reversal of 21181065 is 56018112.

It is not a de Polignac number, because 21181065 - 2⁵ = 21181033 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41277 + ... + 41786.

It is an arithmetic number, because the mean of its divisors is an integer number (2242728).

Almost surely, 2^21181065 is an apocalyptic number.

It is an amenable number.

21181065 is a deficient number, since it is larger than the sum of its proper divisors (14702583).

21181065 is a wasteful number, since it uses less digits than its factorization.

21181065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83088.

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 21181065 is about 4602.2891043480. The cubic root of 21181065 is about 276.6830775253.

Adding to 21181065 its reverse (56018112), we get a palindrome (77199177).

The spelling of 21181065 in words is "twenty-one million, one hundred eighty-one thousand, sixty-five".