65571747821 has 2 divisors, whose sum is σ = 65571747822. Its totient is φ = 65571747820.

The previous prime is 65571747809. The next prime is 65571747841. The reversal of 65571747821 is 12874717556.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65439267721 + 132480100 = 255811^2 + 11510^2 .

It is a cyclic number.

It is not a de Polignac number, because 65571747821 - 2⁶ = 65571747757 is a prime.

It is a super-2 number, since 2×65571747821² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (65571747841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32785873910 + 32785873911.

It is an arithmetic number, because the mean of its divisors is an integer number (32785873911).

Almost surely, 2^65571747821 is an apocalyptic number.

It is an amenable number.

65571747821 is a deficient number, since it is larger than the sum of its proper divisors (1).

65571747821 is an equidigital number, since it uses as much as digits as its factorization.

65571747821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3292800, while the sum is 53.

The spelling of 65571747821 in words is "sixty-five billion, five hundred seventy-one million, seven hundred forty-seven thousand, eight hundred twenty-one".