645881379 has 64 divisors (see below), whose sum is σ = 1046642688. Its totient is φ = 349084800.

The previous prime is 645881333. The next prime is 645881381. The reversal of 645881379 is 973188546.

It is not a de Polignac number, because 645881379 - 2⁷ = 645881251 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645881309) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2076634 + ... + 2076944.

It is an arithmetic number, because the mean of its divisors is an integer number (16353792).

Almost surely, 2^645881379 is an apocalyptic number.

645881379 is a deficient number, since it is larger than the sum of its proper divisors (400761309).

645881379 is a wasteful number, since it uses less digits than its factorization.

645881379 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 488.

The product of its digits is 1451520, while the sum is 51.

The square root of 645881379 is about 25414.1964067330. The cubic root of 645881379 is about 864.4056322035.

The spelling of 645881379 in words is "six hundred forty-five million, eight hundred eighty-one thousand, three hundred seventy-nine".