645871396 has 27 divisors (see below), whose sum is σ = 1150831857. Its totient is φ = 317166720.

The previous prime is 645871381. The next prime is 645871399. The reversal of 645871396 is 693178546.

The square root of 645871396 is 25414.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 290020900 + 355850496 = 17030^2 + 18864^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645871399) 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 8 ways as a sum of consecutive naturals, for example, 4930251 + ... + 4930381.

Almost surely, 2^645871396 is an apocalyptic number.

645871396 is the 25414-th square number.

It is an amenable number.

645871396 is a deficient number, since it is larger than the sum of its proper divisors (504960461).

645871396 is an equidigital number, since it uses as much as digits as its factorization.

645871396 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 460 (or 230 counting only the distinct ones).

The product of its digits is 1088640, while the sum is 49.

The cubic root of 645871396 is about 864.4011786479.

Multiplying 645871396 by its sum of digits (49), we get a square (31647698404 = 177898²).

The spelling of 645871396 in words is "six hundred forty-five million, eight hundred seventy-one thousand, three hundred ninety-six".