11566611551 has 24 divisors (see below), whose sum is σ = 13744656240. Its totient is φ = 9692369280.

The previous prime is 11566611533. The next prime is 11566611569. The reversal of 11566611551 is 15511666511.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (11566611533) and next prime (11566611569).

It is a de Polignac number, because none of the positive numbers 2^k-11566611551 is a prime.

It is a super-4 number, since 4×11566611551⁴ (a number of 41 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11566611451) 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, 17075 + ... + 153051.

It is an arithmetic number, because the mean of its divisors is an integer number (572694010).

Almost surely, 2^11566611551 is an apocalyptic number.

11566611551 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

11566611551 is a deficient number, since it is larger than the sum of its proper divisors (2178044689).

11566611551 is a wasteful number, since it uses less digits than its factorization.

11566611551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136055 (or 136044 counting only the distinct ones).

The product of its digits is 27000, while the sum is 38.

It can be divided in two parts, 115 and 66611551, that added together give a palindrome (66611666).

The spelling of 11566611551 in words is "eleven billion, five hundred sixty-six million, six hundred eleven thousand, five hundred fifty-one".