1605215665 has 16 divisors (see below), whose sum is σ = 2030356800. Its totient is φ = 1214955072.

The previous prime is 1605215663. The next prime is 1605215669. The reversal of 1605215665 is 5665125061.

It is a cyclic number.

It is not a de Polignac number, because 1605215665 - 2¹ = 1605215663 is a prime.

It is a super-2 number, since 2×1605215665² = 5153434662322784450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1605215663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62506 + ... + 84364.

It is an arithmetic number, because the mean of its divisors is an integer number (126897300).

Almost surely, 2^1605215665 is an apocalyptic number.

It is an amenable number.

1605215665 is a deficient number, since it is larger than the sum of its proper divisors (425141135).

1605215665 is a wasteful number, since it uses less digits than its factorization.

1605215665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22656.

The product of its (nonzero) digits is 54000, while the sum is 37.

The square root of 1605215665 is about 40065.1427677476. The cubic root of 1605215665 is about 1170.8766082487.

The spelling of 1605215665 in words is "one billion, six hundred five million, two hundred fifteen thousand, six hundred sixty-five".