1605661992 has 96 divisors (see below), whose sum is σ = 4762143360. Its totient is φ = 484704000.

The previous prime is 1605661991. The next prime is 1605661997. The reversal of 1605661992 is 2991665061.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1605661991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 210892 + ... + 218372.

It is an arithmetic number, because the mean of its divisors is an integer number (49605660).

Almost surely, 2^1605661992 is an apocalyptic number.

1605661992 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1605661992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2381071680).

1605661992 is an abundant number, since it is smaller than the sum of its proper divisors (3156481368).

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

1605661992 is a wasteful number, since it uses less digits than its factorization.

1605661992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7775 (or 7768 counting only the distinct ones).

The product of its (nonzero) digits is 174960, while the sum is 45.

The square root of 1605661992 is about 40070.7123969614. The cubic root of 1605661992 is about 1170.9851181574.

The spelling of 1605661992 in words is "one billion, six hundred five million, six hundred sixty-one thousand, nine hundred ninety-two".