647989 has 8 divisors (see below), whose sum is σ = 701568. Its totient is φ = 596160.

The previous prime is 647987. The next prime is 648007. The reversal of 647989 is 989746.

647989 = T₁₄₂ + T₁₄₃ + ... + T₁₈₈.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 647989 - 2¹ = 647987 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 (647987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 394 + ... + 1204.

It is an arithmetic number, because the mean of its divisors is an integer number (87696).

2⁶⁴⁷⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

647989 is a deficient number, since it is larger than the sum of its proper divisors (53579).

647989 is a wasteful number, since it uses less digits than its factorization.

647989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 875.

The product of its digits is 108864, while the sum is 43.

The square root of 647989 is about 804.9776394410. The cubic root of 647989 is about 86.5344845630.

The spelling of 647989 in words is "six hundred forty-seven thousand, nine hundred eighty-nine".