645442653523 has 4 divisors (see below), whose sum is σ = 649307579760. Its totient is φ = 641577727288.

The previous prime is 645442653503. The next prime is 645442653551. The reversal of 645442653523 is 325356244546.

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-645442653523 is a prime.

It is a super-3 number, since 3×645442653523³ (a number of 36 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645442653503) 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, 1932462868 + ... + 1932463201.

It is an arithmetic number, because the mean of its divisors is an integer number (162326894940).

Almost surely, 2^645442653523 is an apocalyptic number.

645442653523 is a deficient number, since it is larger than the sum of its proper divisors (3864926237).

645442653523 is a wasteful number, since it uses less digits than its factorization.

645442653523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3864926236.

The product of its digits is 10368000, while the sum is 49.

The spelling of 645442653523 in words is "six hundred forty-five billion, four hundred forty-two million, six hundred fifty-three thousand, five hundred twenty-three".