646061778 has 64 divisors (see below), whose sum is σ = 1523975040. Its totient is φ = 202176000.

The previous prime is 646061719. The next prime is 646061783. The reversal of 646061778 is 877160646.

It is an unprimeable 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 31 ways as a sum of consecutive naturals, for example, 551133 + ... + 552303.

It is an arithmetic number, because the mean of its divisors is an integer number (23812110).

Almost surely, 2^646061778 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646061778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (761987520).

646061778 is an abundant number, since it is smaller than the sum of its proper divisors (877913262).

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

646061778 is a wasteful number, since it uses less digits than its factorization.

646061778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1800 (or 1794 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 45.

The square root of 646061778 is about 25417.7453366737. The cubic root of 646061778 is about 864.4861028083.

The spelling of 646061778 in words is "six hundred forty-six million, sixty-one thousand, seven hundred seventy-eight".