1605409799688 has 36 divisors (see below), whose sum is σ = 4348013992335. Its totient is φ = 535133016144.

The previous prime is 1605409799687. The next prime is 1605409799699. The reversal of 1605409799688 is 8869979045061.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

1605409799688 is a `hidden beast` number, since 1 + 6 + 0 + 540 + 9 + 79 + 9 + 6 + 8 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 802704899844 + 802704899844 = 895938^2 + 895938^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=895938.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is not an unprimeable number, because it can be changed into a prime (1605409799687) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 10676595 + ... + 10825917.

Almost surely, 2^{1605409799688} is an apocalyptic number.

1605409799688 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1605409799688 is an abundant number, since it is smaller than the sum of its proper divisors (2742604192647).

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

1605409799688 is an frugal number, since it uses more digits than its factorization.

1605409799688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298658 (or 149328 counting only the distinct ones).

The product of its (nonzero) digits is 235146240, while the sum is 72.

Multiplying 1605409799688 by its sum of digits (72), we get a square (115589505577536 = 10751256²).

1605409799688 divided by its sum of digits (72) gives a square (22297358329 = 149323²).

The spelling of 1605409799688 in words is "one trillion, six hundred five billion, four hundred nine million, seven hundred ninety-nine thousand, six hundred eighty-eight".