11666166601565 has 24 divisors (see below), whose sum is σ = 16292181560760. Its totient is φ = 7996137289728.

The previous prime is 11666166601561. The next prime is 11666166601597. The reversal of 11666166601565 is 56510666166611.

It can be written as a sum of positive squares in 4 ways, for example, as 5859507692164 + 5806658909401 = 2420642^2 + 2409701^2 .

It is not a de Polignac number, because 11666166601565 - 2² = 11666166601561 is a prime.

It is a super-2 number, since 2×11666166601565² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 11666166601565.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11666166601561) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9917600 + ... + 11031369.

It is an arithmetic number, because the mean of its divisors is an integer number (678840898365).

Almost surely, 2^{11666166601565} is an apocalyptic number.

It is an amenable number.

11666166601565 is a deficient number, since it is larger than the sum of its proper divisors (4626014959195).

11666166601565 is a wasteful number, since it uses less digits than its factorization.

11666166601565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20951261 (or 20951254 counting only the distinct ones).

The product of its (nonzero) digits is 6998400, while the sum is 56.

The spelling of 11666166601565 in words is "eleven trillion, six hundred sixty-six billion, one hundred sixty-six million, six hundred one thousand, five hundred sixty-five".