645305349481 has 27 divisors (see below), whose sum is σ = 711107491887. Its totient is φ = 585323069760.

The previous prime is 645305349431. The next prime is 645305349503. The reversal of 645305349481 is 184943503546.

The square root of 645305349481 is 803309.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 218190817881 + 427114531600 = 467109^2 + 653540^2 .

It is not a de Polignac number, because 645305349481 - 2²¹ = 645303252329 is a prime.

It is a super-2 number, since 2×645305349481² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (645305349421) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 637023531 + ... + 637024543.

Almost surely, 2^645305349481 is an apocalyptic number.

645305349481 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

645305349481 is the 803309-th square number.

645305349481 is the 401655-th centered octagonal number.

It is an amenable number.

645305349481 is a deficient number, since it is larger than the sum of its proper divisors (65802142406).

645305349481 is an frugal number, since it uses more digits than its factorization.

645305349481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2174 (or 1087 counting only the distinct ones).

The product of its (nonzero) digits is 6220800, while the sum is 52.

The spelling of 645305349481 in words is "six hundred forty-five billion, three hundred five million, three hundred forty-nine thousand, four hundred eighty-one".