645837839 has 4 divisors (see below), whose sum is σ = 647914800. Its totient is φ = 643760880.

The previous prime is 645837833. The next prime is 645837851. The reversal of 645837839 is 938738546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 938738546 = 2 ⋅469369273.

It is a cyclic number.

It is not a de Polignac number, because 645837839 - 2¹² = 645833743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645837833) by changing a digit.

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, 1038014 + ... + 1038635.

It is an arithmetic number, because the mean of its divisors is an integer number (161978700).

Almost surely, 2^645837839 is an apocalyptic number.

645837839 is a deficient number, since it is larger than the sum of its proper divisors (2076961).

645837839 is a wasteful number, since it uses less digits than its factorization.

645837839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2076960.

The product of its digits is 4354560, while the sum is 53.

The square root of 645837839 is about 25413.3397844518. The cubic root of 645837839 is about 864.3862080656.

The spelling of 645837839 in words is "six hundred forty-five million, eight hundred thirty-seven thousand, eight hundred thirty-nine".