645272605 has 4 divisors (see below), whose sum is σ = 774327132. Its totient is φ = 516218080.

The previous prime is 645272599. The next prime is 645272609. The reversal of 645272605 is 506272546.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 257891481 + 387381124 = 16059^2 + 19682^2 .

It is not a de Polignac number, because 645272605 - 2³ = 645272597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645272609) 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, 64527256 + ... + 64527265.

It is an arithmetic number, because the mean of its divisors is an integer number (193581783).

Almost surely, 2^645272605 is an apocalyptic number.

It is an amenable number.

645272605 is a deficient number, since it is larger than the sum of its proper divisors (129054527).

645272605 is a wasteful number, since it uses less digits than its factorization.

645272605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129054526.

The product of its (nonzero) digits is 100800, while the sum is 37.

The square root of 645272605 is about 25402.2165371449. The cubic root of 645272605 is about 864.1339656562.

The spelling of 645272605 in words is "six hundred forty-five million, two hundred seventy-two thousand, six hundred five".