647990 has 16 divisors (see below), whose sum is σ = 1333152. Its totient is φ = 222144.

The previous prime is 647987. The next prime is 648007. The reversal of 647990 is 99746.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 647990.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 647990.

It is an unprimeable number.

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, 4559 + ... + 4698.

It is an arithmetic number, because the mean of its divisors is an integer number (83322).

2⁶⁴⁷⁹⁹⁰ is an apocalyptic number.

647990 is an abundant number, since it is smaller than the sum of its proper divisors (685162).

It is a weird number, because it is abundant, but not a pseudoperfect number.

647990 is a wasteful number, since it uses less digits than its factorization.

647990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9271.

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 647990 is about 804.9782605760. The cubic root of 647990 is about 86.5345290774.

Adding to 647990 its sum of digits (35), we get a square (648025 = 805²).

The spelling of 647990 in words is "six hundred forty-seven thousand, nine hundred ninety".