645881378 has 8 divisors (see below), whose sum is σ = 985242960. Its totient is φ = 317467060.

The previous prime is 645881333. The next prime is 645881381. The reversal of 645881378 is 873188546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2736668 + ... + 2736903.

It is an arithmetic number, because the mean of its divisors is an integer number (123155370).

Almost surely, 2^645881378 is an apocalyptic number.

645881378 is a deficient number, since it is larger than the sum of its proper divisors (339361582).

645881378 is a wasteful number, since it uses less digits than its factorization.

645881378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5473632.

The product of its digits is 1290240, while the sum is 50.

The square root of 645881378 is about 25414.1963870589. The cubic root of 645881378 is about 864.4056317574.

The spelling of 645881378 in words is "six hundred forty-five million, eight hundred eighty-one thousand, three hundred seventy-eight".