641808121 has 4 divisors (see below), whose sum is σ = 650847744. Its totient is φ = 632768500.

The previous prime is 641808107. The next prime is 641808127. The reversal of 641808121 is 121808146.

641808121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 121808146 = 2 ⋅60904073.

It is a cyclic number.

It is not a de Polignac number, because 641808121 - 2⁹ = 641807609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641808127) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4519705 + ... + 4519846.

It is an arithmetic number, because the mean of its divisors is an integer number (162711936).

Almost surely, 2^641808121 is an apocalyptic number.

It is an amenable number.

641808121 is a deficient number, since it is larger than the sum of its proper divisors (9039623).

641808121 is an equidigital number, since it uses as much as digits as its factorization.

641808121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9039622.

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 641808121 is about 25333.9322056407. The cubic root of 641808121 is about 862.5846709847.

The spelling of 641808121 in words is "six hundred forty-one million, eight hundred eight thousand, one hundred twenty-one".