645261502625 has 8 divisors (see below), whose sum is σ = 805286355432. Its totient is φ = 516209202000.

The previous prime is 645261502619. The next prime is 645261502663. The reversal of 645261502625 is 526205162546.

It can be written as a sum of positive squares in 4 ways, for example, as 1723827361 + 643537675264 = 41519^2 + 802208^2 .

It is not a de Polignac number, because 645261502625 - 2²⁶ = 645194393761 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2581045886 + ... + 2581046135.

It is an arithmetic number, because the mean of its divisors is an integer number (100660794429).

Almost surely, 2^645261502625 is an apocalyptic number.

It is an amenable number.

645261502625 is a deficient number, since it is larger than the sum of its proper divisors (160024852807).

645261502625 is an equidigital number, since it uses as much as digits as its factorization.

645261502625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5162092036 (or 5162092026 counting only the distinct ones).

The product of its (nonzero) digits is 864000, while the sum is 44.

The spelling of 645261502625 in words is "six hundred forty-five billion, two hundred sixty-one million, five hundred two thousand, six hundred twenty-five".