1661111 has 2 divisors, whose sum is σ = 1661112. Its totient is φ = 1661110.

The previous prime is 1661069. The next prime is 1661117. The reversal of 1661111 is 1111661.

It is a strong prime.

It is an emirp because it is prime and its reverse (1111661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1661111 - 2¹⁸ = 1398967 is a prime.

It is a Chen prime.

1661111 is a modest number, since divided by 1111 gives 166 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 1661111.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830555 + 830556.

It is an arithmetic number, because the mean of its divisors is an integer number (830556).

2^1661111 is an apocalyptic number.

1661111 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661111 is an equidigital number, since it uses as much as digits as its factorization.

1661111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36, while the sum is 17.

The square root of 1661111 is about 1288.8409521737. The cubic root of 1661111 is about 118.4312240741.

Adding to 1661111 its reverse (1111661), we get a palindrome (2772772).

The spelling of 1661111 in words is "one million, six hundred sixty-one thousand, one hundred eleven".