1662561665 has 8 divisors (see below), whose sum is σ = 2112431400. Its totient is φ = 1251811072.

The previous prime is 1662561661. The next prime is 1662561673. The reversal of 1662561665 is 5661652661.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 135862336 + 1526699329 = 11656^2 + 39073^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1662561665 - 2² = 1662561661 is a prime.

It is a super-2 number, since 2×1662561665² = 5528222579855144450, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1662561661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9779690 + ... + 9779859.

It is an arithmetic number, because the mean of its divisors is an integer number (264053925).

Almost surely, 2^1662561665 is an apocalyptic number.

It is an amenable number.

1662561665 is a deficient number, since it is larger than the sum of its proper divisors (449869735).

1662561665 is a wasteful number, since it uses less digits than its factorization.

1662561665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19559571.

The product of its digits is 388800, while the sum is 44.

The square root of 1662561665 is about 40774.5222534857. The cubic root of 1662561665 is about 1184.6568977072.

The spelling of 1662561665 in words is "one billion, six hundred sixty-two million, five hundred sixty-one thousand, six hundred sixty-five".