728131645 has 4 divisors (see below), whose sum is σ = 873757980. Its totient is φ = 582505312.

The previous prime is 728131643. The next prime is 728131697. The reversal of 728131645 is 546131827.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 546131827 = 1399 ⋅390373.

It can be written as a sum of positive squares in 2 ways, for example, as 364771801 + 363359844 = 19099^2 + 19062^2 .

It is a cyclic number.

It is not a de Polignac number, because 728131645 - 2¹ = 728131643 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728131643) 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, 72813160 + ... + 72813169.

It is an arithmetic number, because the mean of its divisors is an integer number (218439495).

Almost surely, 2^728131645 is an apocalyptic number.

It is an amenable number.

728131645 is a deficient number, since it is larger than the sum of its proper divisors (145626335).

728131645 is a wasteful number, since it uses less digits than its factorization.

728131645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145626334.

The product of its digits is 40320, while the sum is 37.

The square root of 728131645 is about 26983.9145603450. The cubic root of 728131645 is about 899.6425102834.

The spelling of 728131645 in words is "seven hundred twenty-eight million, one hundred thirty-one thousand, six hundred forty-five".