645204137 has 8 divisors (see below), whose sum is σ = 656187912. Its totient is φ = 634233600.

The previous prime is 645204061. The next prime is 645204163. The reversal of 645204137 is 731402546.

It can be written as a sum of positive squares in 4 ways, for example, as 9357481 + 635846656 = 3059^2 + 25216^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645204137 - 2¹⁰ = 645203113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645203137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 172673 + ... + 176369.

It is an arithmetic number, because the mean of its divisors is an integer number (82023489).

Almost surely, 2^645204137 is an apocalyptic number.

It is an amenable number.

645204137 is a deficient number, since it is larger than the sum of its proper divisors (10983775).

645204137 is a wasteful number, since it uses less digits than its factorization.

645204137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6619.

The product of its (nonzero) digits is 20160, while the sum is 32.

The square root of 645204137 is about 25400.8688237233. The cubic root of 645204137 is about 864.1034009943.

The spelling of 645204137 in words is "six hundred forty-five million, two hundred four thousand, one hundred thirty-seven".