111111101921 has 2 divisors, whose sum is σ = 111111101922. Its totient is φ = 111111101920.

The previous prime is 111111101911. The next prime is 111111101929. The reversal of 111111101921 is 129101111111.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 90673254400 + 20437847521 = 301120^2 + 142961^2 .

It is a cyclic number.

It is not a de Polignac number, because 111111101921 - 2²² = 111106907617 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 111111101893 and 111111101902.

It is not a weakly prime, because it can be changed into another prime (111111101929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55555550960 + 55555550961.

It is an arithmetic number, because the mean of its divisors is an integer number (55555550961).

Almost surely, 2^111111101921 is an apocalyptic number.

It is an amenable number.

111111101921 is a deficient number, since it is larger than the sum of its proper divisors (1).

111111101921 is an equidigital number, since it uses as much as digits as its factorization.

111111101921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18, while the sum is 20.

The spelling of 111111101921 in words is "one hundred eleven billion, one hundred eleven million, one hundred one thousand, nine hundred twenty-one".