645898733 has 4 divisors (see below), whose sum is σ = 666734208. Its totient is φ = 625063260.

The previous prime is 645898727. The next prime is 645898741. The reversal of 645898733 is 337898546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 645898733 - 2⁴ = 645898717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645898703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10417691 + ... + 10417752.

It is an arithmetic number, because the mean of its divisors is an integer number (166683552).

Almost surely, 2^645898733 is an apocalyptic number.

It is an amenable number.

645898733 is a deficient number, since it is larger than the sum of its proper divisors (20835475).

645898733 is a wasteful number, since it uses less digits than its factorization.

645898733 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20835474.

The product of its digits is 4354560, while the sum is 53.

The square root of 645898733 is about 25414.5378277867. The cubic root of 645898733 is about 864.4133739558.

The spelling of 645898733 in words is "six hundred forty-five million, eight hundred ninety-eight thousand, seven hundred thirty-three".