645275729 has 4 divisors (see below), whose sum is σ = 737457984. Its totient is φ = 553093476.

The previous prime is 645275717. The next prime is 645275731. The reversal of 645275729 is 927572546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 927572546 = 2 ⋅463786273.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645275729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645275779) 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, 46091117 + ... + 46091130.

It is an arithmetic number, because the mean of its divisors is an integer number (184364496).

Almost surely, 2^645275729 is an apocalyptic number.

It is an amenable number.

645275729 is a deficient number, since it is larger than the sum of its proper divisors (92182255).

645275729 is an equidigital number, since it uses as much as digits as its factorization.

645275729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92182254.

The product of its digits is 1058400, while the sum is 47.

The square root of 645275729 is about 25402.2780277675. The cubic root of 645275729 is about 864.1353601832.

The spelling of 645275729 in words is "six hundred forty-five million, two hundred seventy-five thousand, seven hundred twenty-nine".