646789890 has 64 divisors (see below), whose sum is σ = 1609896960. Its totient is φ = 166129920.

The previous prime is 646789879. The next prime is 646789901. The reversal of 646789890 is 98987646.

It is an interprime number because it is at equal distance from previous prime (646789879) and next prime (646789901).

It is a self number, because there is not a number n which added to its sum of digits gives 646789890.

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, 211452 + ... + 214488.

It is an arithmetic number, because the mean of its divisors is an integer number (25154640).

Almost surely, 2^646789890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646789890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (804948480).

646789890 is an abundant number, since it is smaller than the sum of its proper divisors (963107070).

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

646789890 is a wasteful number, since it uses less digits than its factorization.

646789890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3307.

The product of its (nonzero) digits is 5225472, while the sum is 57.

The square root of 646789890 is about 25432.0642103625. The cubic root of 646789890 is about 864.8107396640.

The spelling of 646789890 in words is "six hundred forty-six million, seven hundred eighty-nine thousand, eight hundred ninety".