500020991 has 4 divisors (see below), whose sum is σ = 500065800. Its totient is φ = 499976184.

The previous prime is 500020981. The next prime is 500021009. The reversal of 500020991 is 199020005.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 500020991 - 2¹⁴ = 500004607 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 500020991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (500020981) 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, 9125 + ... + 32913.

It is an arithmetic number, because the mean of its divisors is an integer number (125016450).

Almost surely, 2^500020991 is an apocalyptic number.

500020991 is a deficient number, since it is larger than the sum of its proper divisors (44809).

500020991 is a wasteful number, since it uses less digits than its factorization.

500020991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44808.

The product of its (nonzero) digits is 810, while the sum is 26.

The square root of 500020991 is about 22361.1491431009. The cubic root of 500020991 is about 793.7116328738.

Adding to 500020991 its reverse (199020005), we get a palindrome (699040996).

The spelling of 500020991 in words is "five hundred million, twenty thousand, nine hundred ninety-one".