645800409 has 6 divisors (see below), whose sum is σ = 932822826. Its totient is φ = 430533600.

The previous prime is 645800347. The next prime is 645800447. The reversal of 645800409 is 904008546.

645800409 is a `hidden beast` number, since 645 + 8 + 0 + 0 + 4 + 0 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 627652809 + 18147600 = 25053^2 + 4260^2 .

It is not a de Polignac number, because 645800409 - 2¹² = 645796313 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645800459) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35877792 + ... + 35877809.

It is an arithmetic number, because the mean of its divisors is an integer number (155470471).

Almost surely, 2^645800409 is an apocalyptic number.

It is an amenable number.

645800409 is a deficient number, since it is larger than the sum of its proper divisors (287022417).

645800409 is a wasteful number, since it uses less digits than its factorization.

645800409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71755607 (or 71755604 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 645800409 is about 25412.6033495193. The cubic root of 645800409 is about 864.3695090332.

The spelling of 645800409 in words is "six hundred forty-five million, eight hundred thousand, four hundred nine".