645643426 has 8 divisors (see below), whose sum is σ = 972808704. Its totient is φ = 321373860.

The previous prime is 645643393. The next prime is 645643433. The reversal of 645643426 is 624346546.

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

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 3 ways as a sum of consecutive naturals, for example, 723370 + ... + 724261.

It is an arithmetic number, because the mean of its divisors is an integer number (121601088).

Almost surely, 2^645643426 is an apocalyptic number.

645643426 is a deficient number, since it is larger than the sum of its proper divisors (327165278).

645643426 is a wasteful number, since it uses less digits than its factorization.

645643426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1447856.

The product of its digits is 414720, while the sum is 40.

The square root of 645643426 is about 25409.5144778486. The cubic root of 645643426 is about 864.2994655580.

The spelling of 645643426 in words is "six hundred forty-five million, six hundred forty-three thousand, four hundred twenty-six".