645874979 has 4 divisors (see below), whose sum is σ = 668146560. Its totient is φ = 623603400.

The previous prime is 645874967. The next prime is 645875003. The reversal of 645874979 is 979478546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 979478546 = 2 ⋅489739273.

It is a cyclic number.

It is not a de Polignac number, because 645874979 - 2⁴ = 645874963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645874909) 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, 11135747 + ... + 11135804.

It is an arithmetic number, because the mean of its divisors is an integer number (167036640).

Almost surely, 2^645874979 is an apocalyptic number.

645874979 is a deficient number, since it is larger than the sum of its proper divisors (22271581).

645874979 is a wasteful number, since it uses less digits than its factorization.

645874979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22271580.

The product of its digits is 15240960, while the sum is 59.

The square root of 645874979 is about 25414.0704925441. The cubic root of 645874979 is about 864.4027770795.

The spelling of 645874979 in words is "six hundred forty-five million, eight hundred seventy-four thousand, nine hundred seventy-nine".