645413971 has 4 divisors (see below), whose sum is σ = 673475472. Its totient is φ = 617352472.

The previous prime is 645413957. The next prime is 645413981. The reversal of 645413971 is 179314546.

645413971 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 179314546 = 2 ⋅89657273.

It is a cyclic number.

It is not a de Polignac number, because 645413971 - 2⁷ = 645413843 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645413941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14030716 + ... + 14030761.

It is an arithmetic number, because the mean of its divisors is an integer number (168368868).

Almost surely, 2^645413971 is an apocalyptic number.

645413971 is a deficient number, since it is larger than the sum of its proper divisors (28061501).

645413971 is a wasteful number, since it uses less digits than its factorization.

645413971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28061500.

The product of its digits is 90720, while the sum is 40.

The square root of 645413971 is about 25404.9989372171. The cubic root of 645413971 is about 864.1970657277.

The spelling of 645413971 in words is "six hundred forty-five million, four hundred thirteen thousand, nine hundred seventy-one".