641987121 has 4 divisors (see below), whose sum is σ = 855982832. Its totient is φ = 427991412.

The previous prime is 641987117. The next prime is 641987131. The reversal of 641987121 is 121789146.

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.

It is not a de Polignac number, because 641987121 - 2² = 641987117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 641987121.

It is not an unprimeable number, because it can be changed into a prime (641987131) 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, 106997851 + ... + 106997856.

It is an arithmetic number, because the mean of its divisors is an integer number (213995708).

Almost surely, 2^641987121 is an apocalyptic number.

It is an amenable number.

641987121 is a deficient number, since it is larger than the sum of its proper divisors (213995711).

641987121 is a wasteful number, since it uses less digits than its factorization.

641987121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213995710.

The product of its digits is 24192, while the sum is 39.

The square root of 641987121 is about 25337.4647705724. The cubic root of 641987121 is about 862.6648550247.

The spelling of 641987121 in words is "six hundred forty-one million, nine hundred eighty-seven thousand, one hundred twenty-one".