1211011221 has 16 divisors (see below), whose sum is σ = 1895225984. Its totient is φ = 673303104.

The previous prime is 1211011211. The next prime is 1211011237. The reversal of 1211011221 is 1221101121.

It is not a de Polignac number, because 1211011221 - 2⁷ = 1211011093 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211011197 and 1211011206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211011211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 778510 + ... + 780063.

It is an arithmetic number, because the mean of its divisors is an integer number (118451624).

Almost surely, 2^1211011221 is an apocalyptic number.

It is an amenable number.

1211011221 is a deficient number, since it is larger than the sum of its proper divisors (684214763).

1211011221 is a wasteful number, since it uses less digits than its factorization.

1211011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1558620.

The product of its (nonzero) digits is 8, while the sum is 12.

The square root of 1211011221 is about 34799.5865061641. The cubic root of 1211011221 is about 1065.8990024194.

Adding to 1211011221 its reverse (1221101121), we get a palindrome (2432112342).

The spelling of 1211011221 in words is "one billion, two hundred eleven million, eleven thousand, two hundred twenty-one".