65818021 has 4 divisors (see below), whose sum is σ = 65839852. Its totient is φ = 65796192.

The previous prime is 65818013. The next prime is 65818043. The reversal of 65818021 is 12081856.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4368100 + 61449921 = 2090^2 + 7839^2 .

It is a cyclic number.

It is not a de Polignac number, because 65818021 - 2³ = 65818013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65818091) 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, 5496 + ... + 12721.

It is an arithmetic number, because the mean of its divisors is an integer number (16459963).

Almost surely, 2^65818021 is an apocalyptic number.

It is an amenable number.

65818021 is a deficient number, since it is larger than the sum of its proper divisors (21831).

65818021 is a wasteful number, since it uses less digits than its factorization.

65818021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21830.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 65818021 is about 8112.8306404115. The cubic root of 65818021 is about 403.7522355118.

Adding to 65818021 its reverse (12081856), we get a palindrome (77899877).

The spelling of 65818021 in words is "sixty-five million, eight hundred eighteen thousand, twenty-one".