645534681 has 32 divisors (see below), whose sum is σ = 954270720. Its totient is φ = 384907200.

The previous prime is 645534677. The next prime is 645534689. The reversal of 645534681 is 186435546.

It is not a de Polignac number, because 645534681 - 2² = 645534677 is a prime.

It is a super-2 number, since 2×645534681² = 833430048747543522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (645534689) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 607891 + ... + 608951.

It is an arithmetic number, because the mean of its divisors is an integer number (29820960).

Almost surely, 2^645534681 is an apocalyptic number.

It is an amenable number.

645534681 is a deficient number, since it is larger than the sum of its proper divisors (308736039).

645534681 is a wasteful number, since it uses less digits than its factorization.

645534681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1357.

The product of its digits is 345600, while the sum is 42.

The square root of 645534681 is about 25407.3745396883. The cubic root of 645534681 is about 864.2509385027.

The spelling of 645534681 in words is "six hundred forty-five million, five hundred thirty-four thousand, six hundred eighty-one".