16621421806081 has 4 divisors (see below), whose sum is σ = 16621430100052. Its totient is φ = 16621413512112.

The previous prime is 16621421806079. The next prime is 16621421806141. The reversal of 16621421806081 is 18060812412661.

16621421806081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 can be written as a sum of positive squares in 2 ways, for example, as 2398084530625 + 14223337275456 = 1548575^2 + 3771384^2 .

It is a cyclic number.

It is not a de Polignac number, because 16621421806081 - 2¹ = 16621421806079 is a prime.

It is a super-2 number, since 2×16621421806081² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16621421806021) 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, 935011 + ... + 5840983.

It is an arithmetic number, because the mean of its divisors is an integer number (4155357525013).

Almost surely, 2^{16621421806081} is an apocalyptic number.

It is an amenable number.

16621421806081 is a deficient number, since it is larger than the sum of its proper divisors (8293971).

16621421806081 is an equidigital number, since it uses as much as digits as its factorization.

16621421806081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8293970.

The product of its (nonzero) digits is 221184, while the sum is 46.

The spelling of 16621421806081 in words is "sixteen trillion, six hundred twenty-one billion, four hundred twenty-one million, eight hundred six thousand, eighty-one".