11111221 has 8 divisors (see below), whose sum is σ = 12197664. Its totient is φ = 10037520.

The previous prime is 11111209. The next prime is 11111267. The reversal of 11111221 is 12211111.

11111221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11111221 is a prime.

It is a super-2 number, since 2×11111221² = 246918464221682, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 11111198 and 11111207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1306 + ... + 4891.

It is an arithmetic number, because the mean of its divisors is an integer number (1524708).

Almost surely, 2^11111221 is an apocalyptic number.

11111221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11111221 is a deficient number, since it is larger than the sum of its proper divisors (1086443).

11111221 is a wasteful number, since it uses less digits than its factorization.

11111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6371.

The product of its digits is 4, while the sum is 10.

The square root of 11111221 is about 3333.3498166259. The cubic root of 11111221 is about 223.1450523241.

Adding to 11111221 its reverse (12211111), we get a palindrome (23322332).

It can be divided in two parts, 1111 and 1221, that multiplied together give a palindrome (1356531).

The spelling of 11111221 in words is "eleven million, one hundred eleven thousand, two hundred twenty-one".