16555220321405 has 8 divisors (see below), whose sum is σ = 20403190450392. Its totient is φ = 12886225547328.

The previous prime is 16555220321363. The next prime is 16555220321407. The reversal of 16555220321405 is 50412302255561.

It can be written as a sum of positive squares in 4 ways, for example, as 1153213958884 + 15402006362521 = 1073878^2 + 3924539^2 .

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

It is not a de Polignac number, because 16555220321405 - 2²² = 16555216127101 is a prime.

It is a super-2 number, since 2×16555220321405² (a number of 27 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 (16555220321407) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44743838522 + ... + 44743838891.

It is an arithmetic number, because the mean of its divisors is an integer number (2550398806299).

Almost surely, 2^{16555220321405} is an apocalyptic number.

It is an amenable number.

16555220321405 is a deficient number, since it is larger than the sum of its proper divisors (3847970128987).

16555220321405 is an equidigital number, since it uses as much as digits as its factorization.

16555220321405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89487677455.

The product of its (nonzero) digits is 360000, while the sum is 41.

Adding to 16555220321405 its reverse (50412302255561), we get a palindrome (66967522576966).

The spelling of 16555220321405 in words is "sixteen trillion, five hundred fifty-five billion, two hundred twenty million, three hundred twenty-one thousand, four hundred five".