645631533 has 24 divisors (see below), whose sum is σ = 1009497600. Its totient is φ = 407761128.

The previous prime is 645631523. The next prime is 645631549. The reversal of 645631533 is 335136546.

645631533 is a `hidden beast` number, since 64 + 5 + 63 + 1 + 533 = 666.

It is not a de Polignac number, because 645631533 - 2¹⁶ = 645565997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645631523) 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 23 ways as a sum of consecutive naturals, for example, 23373 + ... + 42866.

It is an arithmetic number, because the mean of its divisors is an integer number (42062400).

Almost surely, 2^645631533 is an apocalyptic number.

It is an amenable number.

645631533 is a deficient number, since it is larger than the sum of its proper divisors (363866067).

645631533 is a wasteful number, since it uses less digits than its factorization.

645631533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66286 (or 66261 counting only the distinct ones).

The product of its digits is 97200, while the sum is 36.

The square root of 645631533 is about 25409.2804502607. The cubic root of 645631533 is about 864.2941586160.

The spelling of 645631533 in words is "six hundred forty-five million, six hundred thirty-one thousand, five hundred thirty-three".