1661511005111 has 8 divisors (see below), whose sum is σ = 1678126215600. Its totient is φ = 1644899022400.

The previous prime is 1661511005093. The next prime is 1661511005171. The reversal of 1661511005111 is 1115001151661.

It is a happy number.

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 1661511005111 - 2¹⁴ = 1661510988727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661511005171) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 234395 + ... + 1837923.

It is an arithmetic number, because the mean of its divisors is an integer number (209765776950).

Almost surely, 2^{1661511005111} is an apocalyptic number.

1661511005111 is a deficient number, since it is larger than the sum of its proper divisors (16615210489).

1661511005111 is a wasteful number, since it uses less digits than its factorization.

1661511005111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1613889.

The product of its (nonzero) digits is 900, while the sum is 29.

Adding to 1661511005111 its reverse (1115001151661), we get a palindrome (2776512156772).

The spelling of 1661511005111 in words is "one trillion, six hundred sixty-one billion, five hundred eleven million, five thousand, one hundred eleven".