518394021 has 4 divisors (see below), whose sum is σ = 691192032. Its totient is φ = 345596012.

The previous prime is 518393983. The next prime is 518394031. The reversal of 518394021 is 120493815.

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 518394021 - 2¹⁸ = 518131877 is a prime.

It is a super-2 number, since 2×518394021² = 537464722017096882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (518394031) 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, 86399001 + ... + 86399006.

It is an arithmetic number, because the mean of its divisors is an integer number (172798008).

Almost surely, 2^518394021 is an apocalyptic number.

It is an amenable number.

518394021 is a deficient number, since it is larger than the sum of its proper divisors (172798011).

518394021 is a wasteful number, since it uses less digits than its factorization.

518394021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172798010.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 518394021 is about 22768.2678524301. The cubic root of 518394021 is about 803.3164517074.

The spelling of 518394021 in words is "five hundred eighteen million, three hundred ninety-four thousand, twenty-one".