645640641 has 12 divisors (see below), whose sum is σ = 932813440. Its totient is φ = 430324920.

The previous prime is 645640607. The next prime is 645640643. The reversal of 645640641 is 146046546.

645640641 is a `hidden beast` number, since 6 + 4 + 5 + 6 + 4 + 0 + 641 = 666.

It is not a de Polignac number, because 645640641 - 2⁹ = 645640129 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 645640596 and 645640605.

It is not an unprimeable number, because it can be changed into a prime (645640643) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 64056 + ... + 73446.

Almost surely, 2^645640641 is an apocalyptic number.

It is an amenable number.

645640641 is a deficient number, since it is larger than the sum of its proper divisors (287172799).

645640641 is a wasteful number, since it uses less digits than its factorization.

645640641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17036 (or 17033 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 645640641 is about 25409.4596754831. The cubic root of 645640641 is about 864.2982228300.

The spelling of 645640641 in words is "six hundred forty-five million, six hundred forty thousand, six hundred forty-one".