645724471540 has 12 divisors (see below), whose sum is σ = 1356021390276. Its totient is φ = 258289788608.

The previous prime is 645724471507. The next prime is 645724471543. The reversal of 645724471540 is 45174427546.

It can be written as a sum of positive squares in 2 ways, for example, as 94228125156 + 551496346384 = 306966^2 + 742628^2 .

It is a super-2 number, since 2×645724471540² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645724471543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16143111769 + ... + 16143111808.

It is an arithmetic number, because the mean of its divisors is an integer number (113001782523).

Almost surely, 2^645724471540 is an apocalyptic number.

It is an amenable number.

645724471540 is an abundant number, since it is smaller than the sum of its proper divisors (710296918736).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645724471540 is a wasteful number, since it uses less digits than its factorization.

645724471540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32286223586 (or 32286223584 counting only the distinct ones).

The product of its (nonzero) digits is 3763200, while the sum is 49.

The spelling of 645724471540 in words is "six hundred forty-five billion, seven hundred twenty-four million, four hundred seventy-one thousand, five hundred forty".