645633453181 has 2 divisors, whose sum is σ = 645633453182. Its totient is φ = 645633453180.

The previous prime is 645633453173. The next prime is 645633453239. The reversal of 645633453181 is 181354336546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 458606612025 + 187026841156 = 677205^2 + 432466^2 .

It is a cyclic number.

It is not a de Polignac number, because 645633453181 - 2³ = 645633453173 is a prime.

It is a super-2 number, since 2×645633453181² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645633453581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322816726590 + 322816726591.

It is an arithmetic number, because the mean of its divisors is an integer number (322816726591).

Almost surely, 2^645633453181 is an apocalyptic number.

It is an amenable number.

645633453181 is a deficient number, since it is larger than the sum of its proper divisors (1).

645633453181 is an equidigital number, since it uses as much as digits as its factorization.

645633453181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3110400, while the sum is 49.

The spelling of 645633453181 in words is "six hundred forty-five billion, six hundred thirty-three million, four hundred fifty-three thousand, one hundred eighty-one".