649978 has 16 divisors (see below), whose sum is σ = 1180224. Its totient is φ = 262080.

The previous prime is 649969. The next prime is 649981. The reversal of 649978 is 879946.

It is an unprimeable number.

649978 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1128 + ... + 1603.

It is an arithmetic number, because the mean of its divisors is an integer number (73764).

2⁶⁴⁹⁹⁷⁸ is an apocalyptic number.

649978 is a deficient number, since it is larger than the sum of its proper divisors (530246).

649978 is a wasteful number, since it uses less digits than its factorization.

649978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2757.

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

The square root of 649978 is about 806.2121308936. The cubic root of 649978 is about 86.6229332277.

The spelling of 649978 in words is "six hundred forty-nine thousand, nine hundred seventy-eight".