1605123021908 has 72 divisors (see below), whose sum is σ = 3338937770112. Its totient is φ = 674928936864.

The previous prime is 1605123021883. The next prime is 1605123021917. The reversal of 1605123021908 is 8091203215061.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3337841 + ... + 3788327.

It is an arithmetic number, because the mean of its divisors is an integer number (46374135696).

Almost surely, 2^{1605123021908} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1605123021908, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1669468885056).

1605123021908 is an abundant number, since it is smaller than the sum of its proper divisors (1733814748204).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1605123021908 is an frugal number, since it uses more digits than its factorization.

1605123021908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 450579 (or 450549 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 38.

Adding to 1605123021908 its reverse (8091203215061), we get a palindrome (9696326236969).

The spelling of 1605123021908 in words is "one trillion, six hundred five billion, one hundred twenty-three million, twenty-one thousand, nine hundred eight".