1605670561 has 4 divisors (see below), whose sum is σ = 1751640624. Its totient is φ = 1459700500.

The previous prime is 1605670529. The next prime is 1605670589. The reversal of 1605670561 is 1650765061.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1650765061 = 11 ⋅150069551.

It is a cyclic number.

It is not a de Polignac number, because 1605670561 - 2⁵ = 1605670529 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1605670561.

It is not an unprimeable number, because it can be changed into a prime (1605670361) 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 3 ways as a sum of consecutive naturals, for example, 72985015 + ... + 72985036.

It is an arithmetic number, because the mean of its divisors is an integer number (437910156).

Almost surely, 2^1605670561 is an apocalyptic number.

1605670561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1605670561 is a deficient number, since it is larger than the sum of its proper divisors (145970063).

1605670561 is a wasteful number, since it uses less digits than its factorization.

1605670561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145970062.

The product of its (nonzero) digits is 37800, while the sum is 37.

The square root of 1605670561 is about 40070.8193202984. The cubic root of 1605670561 is about 1170.9872012346.

The spelling of 1605670561 in words is "one billion, six hundred five million, six hundred seventy thousand, five hundred sixty-one".