646971378 has 16 divisors (see below), whose sum is σ = 1324034976. Its totient is φ = 210641760.

The previous prime is 646971373. The next prime is 646971379. The reversal of 646971378 is 873179646.

It is a self number, because there is not a number n which added to its sum of digits gives 646971378.

It is not an unprimeable number, because it can be changed into a prime (646971373) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1253563 + ... + 1254078.

It is an arithmetic number, because the mean of its divisors is an integer number (82752186).

Almost surely, 2^646971378 is an apocalyptic number.

646971378 is an abundant number, since it is smaller than the sum of its proper divisors (677063598).

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

646971378 is a wasteful number, since it uses less digits than its factorization.

646971378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2507689.

The product of its digits is 1524096, while the sum is 51.

The square root of 646971378 is about 25435.6320542659. The cubic root of 646971378 is about 864.8916201766.

The spelling of 646971378 in words is "six hundred forty-six million, nine hundred seventy-one thousand, three hundred seventy-eight".