645687378 has 96 divisors (see below), whose sum is σ = 1674691200. Its totient is φ = 175891968.

The previous prime is 645687377. The next prime is 645687389. The reversal of 645687378 is 873786546.

645687378 is a `hidden beast` number, since 6 + 4 + 568 + 7 + 3 + 78 = 666.

It is not an unprimeable number, because it can be changed into a prime (645687377) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 302218 + ... + 304346.

It is an arithmetic number, because the mean of its divisors is an integer number (17444700).

Almost surely, 2^645687378 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645687378, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (837345600).

645687378 is an abundant number, since it is smaller than the sum of its proper divisors (1029003822).

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

645687378 is a wasteful number, since it uses less digits than its factorization.

645687378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2256 (or 2253 counting only the distinct ones).

The product of its digits is 6773760, while the sum is 54.

The square root of 645687378 is about 25410.3793360115. The cubic root of 645687378 is about 864.3190774297.

The spelling of 645687378 in words is "six hundred forty-five million, six hundred eighty-seven thousand, three hundred seventy-eight".