1221221101 has 4 divisors (see below), whose sum is σ = 1221350400. Its totient is φ = 1221091804.

The previous prime is 1221221093. The next prime is 1221221119. The reversal of 1221221101 is 1011221221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221221101 - 2³ = 1221221093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221224101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49261 + ... + 69778.

It is an arithmetic number, because the mean of its divisors is an integer number (305337600).

Almost surely, 2^1221221101 is an apocalyptic number.

It is an amenable number.

1221221101 is a deficient number, since it is larger than the sum of its proper divisors (129299).

1221221101 is a wasteful number, since it uses less digits than its factorization.

1221221101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129298.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 1221221101 is about 34945.9740313530. The cubic root of 1221221101 is about 1068.8861092865.

Adding to 1221221101 its reverse (1011221221), we get a palindrome (2232442322).

It can be divided in two parts, 1221221 and 101, that multiplied together give a palindrome (123343321).

The spelling of 1221221101 in words is "one billion, two hundred twenty-one million, two hundred twenty-one thousand, one hundred one".