645664770725 has 12 divisors (see below), whose sum is σ = 862210801956. Its totient is φ = 476798599680.

The previous prime is 645664770697. The next prime is 645664770787. The reversal of 645664770725 is 527077466546.

It can be written as a sum of positive squares in 6 ways, for example, as 143939048449 + 501725722276 = 379393^2 + 708326^2 .

It is not a de Polignac number, because 645664770725 - 2¹⁸ = 645664508581 is a prime.

It is a hoax number, since the sum of its digits (59) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 993330092 + ... + 993330741.

It is an arithmetic number, because the mean of its divisors is an integer number (71850900163).

Almost surely, 2^645664770725 is an apocalyptic number.

645664770725 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

645664770725 is a deficient number, since it is larger than the sum of its proper divisors (216546031231).

645664770725 is a wasteful number, since it uses less digits than its factorization.

645664770725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1986660856 (or 1986660851 counting only the distinct ones).

The product of its (nonzero) digits is 59270400, while the sum is 59.

The spelling of 645664770725 in words is "six hundred forty-five billion, six hundred sixty-four million, seven hundred seventy thousand, seven hundred twenty-five".