645863808 has 64 divisors (see below), whose sum is σ = 1805889600. Its totient is φ = 203954688.

The previous prime is 645863797. The next prime is 645863809. The reversal of 645863808 is 808368546.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645863809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36966 + ... + 51557.

It is an arithmetic number, because the mean of its divisors is an integer number (28217025).

Almost surely, 2^645863808 is an apocalyptic number.

It is an amenable number.

645863808 is an abundant number, since it is smaller than the sum of its proper divisors (1160025792).

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

645863808 is a wasteful number, since it uses less digits than its factorization.

645863808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88559 (or 88547 counting only the distinct ones).

The product of its (nonzero) digits is 1105920, while the sum is 48.

The square root of 645863808 is about 25413.8507117674. The cubic root of 645863808 is about 864.3977935045.

The spelling of 645863808 in words is "six hundred forty-five million, eight hundred sixty-three thousand, eight hundred eight".