641878163661 has 16 divisors (see below), whose sum is σ = 991498692224. Its totient is φ = 361763034624.

The previous prime is 641878163659. The next prime is 641878163671. The reversal of 641878163661 is 166361878146.

641878163661 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 641878163661 - 2¹ = 641878163659 is a prime.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641878163621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 209352076 + ... + 209355141.

It is an arithmetic number, because the mean of its divisors is an integer number (61968668264).

Almost surely, 2^641878163661 is an apocalyptic number.

It is an amenable number.

641878163661 is a deficient number, since it is larger than the sum of its proper divisors (349620528563).

641878163661 is a wasteful number, since it uses less digits than its factorization.

641878163661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418707300.

The product of its digits is 6967296, while the sum is 57.

The spelling of 641878163661 in words is "six hundred forty-one billion, eight hundred seventy-eight million, one hundred sixty-three thousand, six hundred sixty-one".