649778 has 4 divisors (see below), whose sum is σ = 974670. Its totient is φ = 324888.

The previous prime is 649777. The next prime is 649783. The reversal of 649778 is 877946.

649778 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 573049 + 76729 = 757^2 + 277^2 .

It is a super-2 number, since 2×649778² = 844422898568, which contains 22 as substring.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (649771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 162443 + ... + 162446.

2⁶⁴⁹⁷⁷⁸ is an apocalyptic number.

649778 is a deficient number, since it is larger than the sum of its proper divisors (324892).

649778 is a wasteful number, since it uses less digits than its factorization.

649778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324891.

The product of its digits is 84672, while the sum is 41.

The square root of 649778 is about 806.0880845168. The cubic root of 649778 is about 86.6140476121.

The spelling of 649778 in words is "six hundred forty-nine thousand, seven hundred seventy-eight".