645494291 has 4 divisors (see below), whose sum is σ = 695147712. Its totient is φ = 595840872.

The previous prime is 645494273. The next prime is 645494293. The reversal of 645494291 is 192494546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 192494546 = 2 ⋅96247273.

It is a cyclic number.

It is not a de Polignac number, because 645494291 - 2¹⁰ = 645493267 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645494293) 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, 24826691 + ... + 24826716.

It is an arithmetic number, because the mean of its divisors is an integer number (173786928).

Almost surely, 2^645494291 is an apocalyptic number.

645494291 is a deficient number, since it is larger than the sum of its proper divisors (49653421).

645494291 is a wasteful number, since it uses less digits than its factorization.

645494291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49653420.

The product of its digits is 311040, while the sum is 44.

The square root of 645494291 is about 25406.5796792878. The cubic root of 645494291 is about 864.2329132262.

The spelling of 645494291 in words is "six hundred forty-five million, four hundred ninety-four thousand, two hundred ninety-one".