645235639776 has 960 divisors, whose sum is σ = 2443575214080. Its totient is φ = 162452459520.

The previous prime is 645235639771. The next prime is 645235639799. The reversal of 645235639776 is 677936532546.

645235639776 is a `hidden beast` number, since 6 + 4 + 5 + 235 + 6 + 397 + 7 + 6 = 666.

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645235639771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 577649970 + ... + 577651086.

It is an arithmetic number, because the mean of its divisors is an integer number (2545390848).

Almost surely, 2^645235639776 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645235639776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1221787607040).

645235639776 is an abundant number, since it is smaller than the sum of its proper divisors (1798339574304).

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

645235639776 is a wasteful number, since it uses less digits than its factorization.

645235639776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1269 (or 1252 counting only the distinct ones).

The product of its digits is 171460800, while the sum is 63.

The spelling of 645235639776 in words is "six hundred forty-five billion, two hundred thirty-five million, six hundred thirty-nine thousand, seven hundred seventy-six".