111621661 has 2 divisors, whose sum is σ = 111621662. Its totient is φ = 111621660.

The previous prime is 111621659. The next prime is 111621689. The reversal of 111621661 is 166126111.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 84529636 + 27092025 = 9194^2 + 5205^2 .

It is an emirp because it is prime and its reverse (166126111) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 111621661 - 2¹ = 111621659 is a prime.

Together with 111621659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111621641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55810830 + 55810831.

It is an arithmetic number, because the mean of its divisors is an integer number (55810831).

Almost surely, 2^111621661 is an apocalyptic number.

It is an amenable number.

111621661 is a deficient number, since it is larger than the sum of its proper divisors (1).

111621661 is an equidigital number, since it uses as much as digits as its factorization.

111621661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 25.

The square root of 111621661 is about 10565.1152856938. The cubic root of 111621661 is about 481.4850721818.

Adding to 111621661 its reverse (166126111), we get a palindrome (277747772).

The spelling of 111621661 in words is "one hundred eleven million, six hundred twenty-one thousand, six hundred sixty-one".