111721421 has 6 divisors (see below), whose sum is σ = 129961710. Its totient is φ = 95761176.

The previous prime is 111721417. The next prime is 111721429. The reversal of 111721421 is 124127111.

It can be written as a sum of positive squares in only one way, i.e., 110544196 + 1177225 = 10514^2 + 1085^2 .

It is not a de Polignac number, because 111721421 - 2² = 111721417 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 111721393 and 111721402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111721429) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1139966 + ... + 1140063.

It is an arithmetic number, because the mean of its divisors is an integer number (21660285).

Almost surely, 2^111721421 is an apocalyptic number.

It is an amenable number.

111721421 is a deficient number, since it is larger than the sum of its proper divisors (18240289).

111721421 is an equidigital number, since it uses as much as digits as its factorization.

111721421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2280043 (or 2280036 counting only the distinct ones).

The product of its digits is 112, while the sum is 20.

The square root of 111721421 is about 10569.8354291824. The cubic root of 111721421 is about 481.6284692247.

Adding to 111721421 its reverse (124127111), we get a palindrome (235848532).

The spelling of 111721421 in words is "one hundred eleven million, seven hundred twenty-one thousand, four hundred twenty-one".