645155540 has 12 divisors (see below), whose sum is σ = 1354826676. Its totient is φ = 258062208.

The previous prime is 645155527. The next prime is 645155549. The reversal of 645155540 is 45551546.

It can be written as a sum of positive squares in 2 ways, for example, as 218980804 + 426174736 = 14798^2 + 20644^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 645155540.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645155549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16128869 + ... + 16128908.

It is an arithmetic number, because the mean of its divisors is an integer number (112902223).

Almost surely, 2^645155540 is an apocalyptic number.

It is an amenable number.

645155540 is an abundant number, since it is smaller than the sum of its proper divisors (709671136).

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

645155540 is a wasteful number, since it uses less digits than its factorization.

645155540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32257786 (or 32257784 counting only the distinct ones).

The product of its (nonzero) digits is 60000, while the sum is 35.

The square root of 645155540 is about 25399.9122045727. The cubic root of 645155540 is about 864.0817055933.

The spelling of 645155540 in words is "six hundred forty-five million, one hundred fifty-five thousand, five hundred forty".