1661111611 has 2 divisors, whose sum is σ = 1661111612. Its totient is φ = 1661111610.

The previous prime is 1661111603. The next prime is 1661111659. The reversal of 1661111611 is 1161111661.

It is a weak prime.

It is an emirp because it is prime and its reverse (1161111661) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1191111991 and 1991111911.

It is a cyclic number.

It is not a de Polignac number, because 1661111611 - 2³ = 1661111603 is a prime.

It is not a weakly prime, because it can be changed into another prime (1661111671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830555805 + 830555806.

It is an arithmetic number, because the mean of its divisors is an integer number (830555806).

Almost surely, 2^1661111611 is an apocalyptic number.

1661111611 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661111611 is an equidigital number, since it uses as much as digits as its factorization.

1661111611 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216, while the sum is 25.

The square root of 1661111611 is about 40756.7370013842. The cubic root of 1661111611 is about 1184.3123859483.

The spelling of 1661111611 in words is "one billion, six hundred sixty-one million, one hundred eleven thousand, six hundred eleven".