645331538 has 16 divisors (see below), whose sum is σ = 986152320. Its totient is φ = 316650576.

The previous prime is 645331537. The next prime is 645331549. The reversal of 645331538 is 835133546.

It is not an unprimeable number, because it can be changed into a prime (645331537) 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 7 ways as a sum of consecutive naturals, for example, 27095 + ... + 44997.

It is an arithmetic number, because the mean of its divisors is an integer number (61634520).

Almost surely, 2^645331538 is an apocalyptic number.

645331538 is a deficient number, since it is larger than the sum of its proper divisors (340820782).

645331538 is a wasteful number, since it uses less digits than its factorization.

645331538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18241.

The product of its digits is 129600, while the sum is 38.

The square root of 645331538 is about 25403.3765078582. The cubic root of 645331538 is about 864.1602720867.

The spelling of 645331538 in words is "six hundred forty-five million, three hundred thirty-one thousand, five hundred thirty-eight".