645399625 has 32 divisors (see below), whose sum is σ = 870498720. Its totient is φ = 474912000.

The previous prime is 645399607. The next prime is 645399647. The reversal of 645399625 is 526993546.

It is a happy number.

It can be written as a sum of positive squares in 16 ways, for example, as 596287561 + 49112064 = 24419^2 + 7008^2 .

It is not a de Polignac number, because 645399625 - 2⁵ = 645399593 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 631615 + ... + 632635.

It is an arithmetic number, because the mean of its divisors is an integer number (27203085).

Almost surely, 2^645399625 is an apocalyptic number.

645399625 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

645399625 is a deficient number, since it is larger than the sum of its proper divisors (225099095).

645399625 is a wasteful number, since it uses less digits than its factorization.

645399625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1438 (or 1428 counting only the distinct ones).

The product of its digits is 1749600, while the sum is 49.

The square root of 645399625 is about 25404.7165896414. The cubic root of 645399625 is about 864.1906626729.

The spelling of 645399625 in words is "six hundred forty-five million, three hundred ninety-nine thousand, six hundred twenty-five".