645799620197 has 4 divisors (see below), whose sum is σ = 659540037696. Its totient is φ = 632059202700.

The previous prime is 645799620163. The next prime is 645799620199. The reversal of 645799620197 is 791026997546.

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.

It is a cyclic number.

It is not a de Polignac number, because 645799620197 - 2¹⁸ = 645799358053 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 (645799620199) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6870208679 + ... + 6870208772.

It is an arithmetic number, because the mean of its divisors is an integer number (164885009424).

Almost surely, 2^645799620197 is an apocalyptic number.

It is an amenable number.

645799620197 is a deficient number, since it is larger than the sum of its proper divisors (13740417499).

645799620197 is a wasteful number, since it uses less digits than its factorization.

645799620197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13740417498.

The product of its (nonzero) digits is 51438240, while the sum is 65.

The spelling of 645799620197 in words is "six hundred forty-five billion, seven hundred ninety-nine million, six hundred twenty thousand, one hundred ninety-seven".