645424985 has 4 divisors (see below), whose sum is σ = 774509988. Its totient is φ = 516339984.

The previous prime is 645424961. The next prime is 645424987. The reversal of 645424985 is 589424546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 589424546 = 2 ⋅294712273.

It can be written as a sum of positive squares in 2 ways, for example, as 121793296 + 523631689 = 11036^2 + 22883^2 .

It is a cyclic number.

It is not a de Polignac number, because 645424985 - 2¹² = 645420889 is a prime.

It is a super-2 number, since 2×645424985² = 833146822524500450, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645424987) 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, 64542494 + ... + 64542503.

It is an arithmetic number, because the mean of its divisors is an integer number (193627497).

Almost surely, 2^645424985 is an apocalyptic number.

It is an amenable number.

645424985 is a deficient number, since it is larger than the sum of its proper divisors (129085003).

645424985 is a wasteful number, since it uses less digits than its factorization.

645424985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129085002.

The product of its digits is 1382400, while the sum is 47.

The square root of 645424985 is about 25405.2157046540. The cubic root of 645424985 is about 864.2019815454.

The spelling of 645424985 in words is "six hundred forty-five million, four hundred twenty-four thousand, nine hundred eighty-five".