21140565 has 32 divisors (see below), whose sum is σ = 36529920. Its totient is φ = 10407936.

The previous prime is 21140549. The next prime is 21140569. The reversal of 21140565 is 56504112.

21140565 = 575² + 576² + ... + 632².

It is not a de Polignac number, because 21140565 - 2⁴ = 21140549 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21140569) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8949 + ... + 11061.

It is an arithmetic number, because the mean of its divisors is an integer number (1141560).

Almost surely, 2^21140565 is an apocalyptic number.

It is an amenable number.

21140565 is a deficient number, since it is larger than the sum of its proper divisors (15389355).

21140565 is a wasteful number, since it uses less digits than its factorization.

21140565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2173.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21140565 is about 4597.8870147058. The cubic root of 21140565 is about 276.5066178069.

Adding to 21140565 its reverse (56504112), we get a palindrome (77644677).

The spelling of 21140565 in words is "twenty-one million, one hundred forty thousand, five hundred sixty-five".