649686840 has 128 divisors (see below), whose sum is σ = 2194974720. Its totient is φ = 152409600.

The previous prime is 649686827. The next prime is 649686857. The reversal of 649686840 is 48686946.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32982 + ... + 48858.

It is an arithmetic number, because the mean of its divisors is an integer number (17148240).

Almost surely, 2^649686840 is an apocalyptic number.

649686840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 649686840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1097487360).

649686840 is an abundant number, since it is smaller than the sum of its proper divisors (1545287880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

649686840 is a wasteful number, since it uses less digits than its factorization.

649686840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15933 (or 15929 counting only the distinct ones).

The product of its (nonzero) digits is 1990656, while the sum is 51.

The square root of 649686840 is about 25488.9552551689. The cubic root of 649686840 is about 866.0999694359.

The spelling of 649686840 in words is "six hundred forty-nine million, six hundred eighty-six thousand, eight hundred forty".