641191968 has 72 divisors (see below), whose sum is σ = 1830065328. Its totient is φ = 212948352.

The previous prime is 641191961. The next prime is 641191973. The reversal of 641191968 is 869191146.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×641191968² = 822254279655426048, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (641191961) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 77571 + ... + 85437.

It is an arithmetic number, because the mean of its divisors is an integer number (25417574).

Almost surely, 2^641191968 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 641191968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (915032664).

641191968 is an abundant number, since it is smaller than the sum of its proper divisors (1188873360).

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

641191968 is a wasteful number, since it uses less digits than its factorization.

641191968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8166 (or 8155 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 641191968 is about 25321.7686586068. The cubic root of 641191968 is about 862.3085478020.

The spelling of 641191968 in words is "six hundred forty-one million, one hundred ninety-one thousand, nine hundred sixty-eight".