65217821 has 8 divisors (see below), whose sum is σ = 66027864. Its totient is φ = 64411200.

The previous prime is 65217793. The next prime is 65217847. The reversal of 65217821 is 12871256.

It can be written as a sum of positive squares in 4 ways, for example, as 13579225 + 51638596 = 3685^2 + 7186^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 65217821 - 2²² = 61023517 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 (65217881) 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, 76031 + ... + 76883.

It is an arithmetic number, because the mean of its divisors is an integer number (8253483).

Almost surely, 2^65217821 is an apocalyptic number.

It is an amenable number.

65217821 is a deficient number, since it is larger than the sum of its proper divisors (810043).

65217821 is a wasteful number, since it uses less digits than its factorization.

65217821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1711.

The product of its digits is 6720, while the sum is 32.

The square root of 65217821 is about 8075.7551349704. The cubic root of 65217821 is about 402.5212025404.

The spelling of 65217821 in words is "sixty-five million, two hundred seventeen thousand, eight hundred twenty-one".