665651055281 has 2 divisors, whose sum is σ = 665651055282. Its totient is φ = 665651055280.

The previous prime is 665651055151. The next prime is 665651055287. The reversal of 665651055281 is 182550156566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 616374159025 + 49276896256 = 785095^2 + 221984^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665651055281 is a prime.

It is a super-2 number, since 2×665651055281² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (665651055287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332825527640 + 332825527641.

It is an arithmetic number, because the mean of its divisors is an integer number (332825527641).

Almost surely, 2^665651055281 is an apocalyptic number.

It is an amenable number.

665651055281 is a deficient number, since it is larger than the sum of its proper divisors (1).

665651055281 is an equidigital number, since it uses as much as digits as its factorization.

665651055281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160000, while the sum is 50.

The spelling of 665651055281 in words is "six hundred sixty-five billion, six hundred fifty-one million, fifty-five thousand, two hundred eighty-one".