645194438320 has 40 divisors (see below), whose sum is σ = 1551803870160. Its totient is φ = 249178540800.

The previous prime is 645194438311. The next prime is 645194438333. The reversal of 645194438320 is 23834491546.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 139048206 + ... + 139052845.

It is an arithmetic number, because the mean of its divisors is an integer number (38795096754).

Almost surely, 2^645194438320 is an apocalyptic number.

It is an amenable number.

645194438320 is an abundant number, since it is smaller than the sum of its proper divisors (906609431840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645194438320 is a wasteful number, since it uses less digits than its factorization.

645194438320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278101093 (or 278101087 counting only the distinct ones).

The product of its (nonzero) digits is 2488320, while the sum is 49.

The spelling of 645194438320 in words is "six hundred forty-five billion, one hundred ninety-four million, four hundred thirty-eight thousand, three hundred twenty".