518861821 has 4 divisors (see below), whose sum is σ = 522298144. Its totient is φ = 515425500.

The previous prime is 518861797. The next prime is 518861843. The reversal of 518861821 is 128168815.

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 a cyclic number.

It is not a de Polignac number, because 518861821 - 2⁵ = 518861789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (518861851) 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, 1717935 + ... + 1718236.

It is an arithmetic number, because the mean of its divisors is an integer number (130574536).

Almost surely, 2^518861821 is an apocalyptic number.

It is an amenable number.

518861821 is a deficient number, since it is larger than the sum of its proper divisors (3436323).

518861821 is a wasteful number, since it uses less digits than its factorization.

518861821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3436322.

The product of its digits is 30720, while the sum is 40.

The square root of 518861821 is about 22778.5386054505. The cubic root of 518861821 is about 803.5580172857.

The spelling of 518861821 in words is "five hundred eighteen million, eight hundred sixty-one thousand, eight hundred twenty-one".