641987 has 4 divisors (see below), whose sum is σ = 659376. Its totient is φ = 624600.

The previous prime is 641981. The next prime is 642011. The reversal of 641987 is 789146.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 641987 - 2⁶ = 641923 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8639 + ... + 8712.

It is an arithmetic number, because the mean of its divisors is an integer number (164844).

2⁶⁴¹⁹⁸⁷ is an apocalyptic number.

641987 is a deficient number, since it is larger than the sum of its proper divisors (17389).

641987 is a wasteful number, since it uses less digits than its factorization.

641987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17388.

The product of its digits is 12096, while the sum is 35.

The square root of 641987 is about 801.2409125850. The cubic root of 641987 is about 86.2664800827.

The spelling of 641987 in words is "six hundred forty-one thousand, nine hundred eighty-seven".