645638534 has 16 divisors (see below), whose sum is σ = 986437440. Its totient is φ = 316843560.

The previous prime is 645638509. The next prime is 645638537. The reversal of 645638534 is 435836546.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645638537) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76589 + ... + 84599.

It is an arithmetic number, because the mean of its divisors is an integer number (61652340).

Almost surely, 2^645638534 is an apocalyptic number.

645638534 is a deficient number, since it is larger than the sum of its proper divisors (340798906).

645638534 is a wasteful number, since it uses less digits than its factorization.

645638534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8755.

The product of its digits is 1036800, while the sum is 44.

The square root of 645638534 is about 25409.4182145125. The cubic root of 645638534 is about 864.2972826381.

The spelling of 645638534 in words is "six hundred forty-five million, six hundred thirty-eight thousand, five hundred thirty-four".