16555220321657 has 2 divisors, whose sum is σ = 16555220321658. Its totient is φ = 16555220321656.

The previous prime is 16555220321617. The next prime is 16555220321659. The reversal of 16555220321657 is 75612302255561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14644865113321 + 1910355208336 = 3826861^2 + 1382156^2 .

It is a cyclic number.

It is not a de Polignac number, because 16555220321657 - 2¹⁶ = 16555220256121 is a prime.

Together with 16555220321659, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (16555220321659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8277610160828 + 8277610160829.

It is an arithmetic number, because the mean of its divisors is an integer number (8277610160829).

Almost surely, 2^{16555220321657} is an apocalyptic number.

It is an amenable number.

16555220321657 is a deficient number, since it is larger than the sum of its proper divisors (1).

16555220321657 is an equidigital number, since it uses as much as digits as its factorization.

16555220321657 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3780000, while the sum is 50.

The spelling of 16555220321657 in words is "sixteen trillion, five hundred fifty-five billion, two hundred twenty million, three hundred twenty-one thousand, six hundred fifty-seven".