645233621 has 8 divisors (see below), whose sum is σ = 652521240. Its totient is φ = 637959168.

The previous prime is 645233609. The next prime is 645233671. The reversal of 645233621 is 126332546.

It can be written as a sum of positive squares in 4 ways, for example, as 312900721 + 332332900 = 17689^2 + 18230^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645233621 - 2¹⁰ = 645232597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645233671) 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 7 ways as a sum of consecutive naturals, for example, 121265 + ... + 126473.

It is an arithmetic number, because the mean of its divisors is an integer number (81565155).

Almost surely, 2^645233621 is an apocalyptic number.

It is an amenable number.

645233621 is a deficient number, since it is larger than the sum of its proper divisors (7287619).

645233621 is a wasteful number, since it uses less digits than its factorization.

645233621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6583.

The product of its digits is 25920, while the sum is 32.

The square root of 645233621 is about 25401.4491909418. The cubic root of 645233621 is about 864.1165631524.

The spelling of 645233621 in words is "six hundred forty-five million, two hundred thirty-three thousand, six hundred twenty-one".