646605389 has 4 divisors (see below), whose sum is σ = 651541440. Its totient is φ = 641669340.

The previous prime is 646605361. The next prime is 646605439. The reversal of 646605389 is 983506646.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 983506646 = 2 ⋅491753323.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646605389 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 (646605329) 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, 2467829 + ... + 2468090.

It is an arithmetic number, because the mean of its divisors is an integer number (162885360).

Almost surely, 2^646605389 is an apocalyptic number.

It is an amenable number.

646605389 is a deficient number, since it is larger than the sum of its proper divisors (4936051).

646605389 is a wasteful number, since it uses less digits than its factorization.

646605389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4936050.

The product of its (nonzero) digits is 933120, while the sum is 47.

The square root of 646605389 is about 25428.4366212318. The cubic root of 646605389 is about 864.7285008912.

The spelling of 646605389 in words is "six hundred forty-six million, six hundred five thousand, three hundred eighty-nine".