16520020421 has 8 divisors (see below), whose sum is σ = 17403998400. Its totient is φ = 15637492800.

The previous prime is 16520020399. The next prime is 16520020441. The reversal of 16520020421 is 12402002561.

It is a happy number.

16520020421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16520020421 - 2⁶ = 16520020357 is a prime.

It is a super-2 number, since 2×16520020421² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16520020441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 339161 + ... + 384798.

It is an arithmetic number, because the mean of its divisors is an integer number (2175499800).

Almost surely, 2^16520020421 is an apocalyptic number.

It is an amenable number.

16520020421 is a deficient number, since it is larger than the sum of its proper divisors (883977979).

16520020421 is a wasteful number, since it uses less digits than its factorization.

16520020421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725179.

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 16520020421 its reverse (12402002561), we get a palindrome (28922022982).

The spelling of 16520020421 in words is "sixteen billion, five hundred twenty million, twenty thousand, four hundred twenty-one".