641688081 has 8 divisors (see below), whose sum is σ = 856896960. Its totient is φ = 427135632.

The previous prime is 641688029. The next prime is 641688107. The reversal of 641688081 is 180886146.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-641688081 is a prime.

It is a super-2 number, since 2×641688081² = 823527186594925122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (641688181) 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, 161821 + ... + 165738.

It is an arithmetic number, because the mean of its divisors is an integer number (107112120).

Almost surely, 2^641688081 is an apocalyptic number.

It is an amenable number.

641688081 is a deficient number, since it is larger than the sum of its proper divisors (215208879).

641688081 is a wasteful number, since it uses less digits than its factorization.

641688081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328215.

The product of its (nonzero) digits is 73728, while the sum is 42.

The square root of 641688081 is about 25331.5629403320. The cubic root of 641688081 is about 862.5308900510.

The spelling of 641688081 in words is "six hundred forty-one million, six hundred eighty-eight thousand, eighty-one".