646191355440 has 160 divisors (see below), whose sum is σ = 2029810798080. Its totient is φ = 170039881728.

The previous prime is 646191355427. The next prime is 646191355541. The reversal of 646191355440 is 44553191646.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 646191355440.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6949576 + ... + 7041944.

It is an arithmetic number, because the mean of its divisors is an integer number (12686317488).

Almost surely, 2^646191355440 is an apocalyptic number.

646191355440 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 646191355440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1014905399040).

646191355440 is an abundant number, since it is smaller than the sum of its proper divisors (1383619442640).

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

646191355440 is a wasteful number, since it uses less digits than its factorization.

646191355440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92771 (or 92765 counting only the distinct ones).

The product of its (nonzero) digits is 1555200, while the sum is 48.

The spelling of 646191355440 in words is "six hundred forty-six billion, one hundred ninety-one million, three hundred fifty-five thousand, four hundred forty".