645556199 has 4 divisors (see below), whose sum is σ = 648800400. Its totient is φ = 642312000.

The previous prime is 645556151. The next prime is 645556201. The reversal of 645556199 is 991655546.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645556199 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 (645556099) 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, 1621802 + ... + 1622199.

It is an arithmetic number, because the mean of its divisors is an integer number (162200100).

Almost surely, 2^645556199 is an apocalyptic number.

645556199 is a deficient number, since it is larger than the sum of its proper divisors (3244201).

645556199 is a wasteful number, since it uses less digits than its factorization.

645556199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3244200.

The product of its digits is 1458000, while the sum is 50.

The square root of 645556199 is about 25407.7979958909. The cubic root of 645556199 is about 864.2605412634.

The spelling of 645556199 in words is "six hundred forty-five million, five hundred fifty-six thousand, one hundred ninety-nine".