1605899450581 has 2 divisors, whose sum is σ = 1605899450582. Its totient is φ = 1605899450580.

The previous prime is 1605899450579. The next prime is 1605899450587. The reversal of 1605899450581 is 1850549985061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1340477684100 + 265421766481 = 1157790^2 + 515191^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605899450581 - 2¹ = 1605899450579 is a prime.

It is a super-2 number, since 2×1605899450581² (a number of 25 digits) contains 22 as substring.

Together with 1605899450579, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1605899450587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802949725290 + 802949725291.

It is an arithmetic number, because the mean of its divisors is an integer number (802949725291).

Almost surely, 2^{1605899450581} is an apocalyptic number.

It is an amenable number.

1605899450581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605899450581 is an equidigital number, since it uses as much as digits as its factorization.

1605899450581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552000, while the sum is 61.

The spelling of 1605899450581 in words is "one trillion, six hundred five billion, eight hundred ninety-nine million, four hundred fifty thousand, five hundred eighty-one".