645864451 has 4 divisors (see below), whose sum is σ = 647968552. Its totient is φ = 643760352.

The previous prime is 645864437. The next prime is 645864463. The reversal of 645864451 is 154468546.

645864451 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.

It is a cyclic number.

It is not a de Polignac number, because 645864451 - 2²⁵ = 612310019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645864398 and 645864407.

It is not an unprimeable number, because it can be changed into a prime (645864151) 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, 1051590 + ... + 1052203.

It is an arithmetic number, because the mean of its divisors is an integer number (161992138).

Almost surely, 2^645864451 is an apocalyptic number.

645864451 is a deficient number, since it is larger than the sum of its proper divisors (2104101).

645864451 is a wasteful number, since it uses less digits than its factorization.

645864451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2104100.

The product of its digits is 460800, while the sum is 43.

The square root of 645864451 is about 25413.8633623462. The cubic root of 645864451 is about 864.3980803594.

The spelling of 645864451 in words is "six hundred forty-five million, eight hundred sixty-four thousand, four hundred fifty-one".