645735839 has 4 divisors (see below), whose sum is σ = 737983824. Its totient is φ = 553487856.

The previous prime is 645735791. The next prime is 645735863. The reversal of 645735839 is 938537546.

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 645735839 - 2¹⁶ = 645670303 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 (645735869) 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, 46123982 + ... + 46123995.

It is an arithmetic number, because the mean of its divisors is an integer number (184495956).

Almost surely, 2^645735839 is an apocalyptic number.

645735839 is a deficient number, since it is larger than the sum of its proper divisors (92247985).

645735839 is an equidigital number, since it uses as much as digits as its factorization.

645735839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92247984.

The product of its digits is 2721600, while the sum is 50.

The square root of 645735839 is about 25411.3328851519. The cubic root of 645735839 is about 864.3407002358.

The spelling of 645735839 in words is "six hundred forty-five million, seven hundred thirty-five thousand, eight hundred thirty-nine".