1221331011 has 4 divisors (see below), whose sum is σ = 1628441352. Its totient is φ = 814220672.

The previous prime is 1221331009. The next prime is 1221331019. The reversal of 1221331011 is 1101331221.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1101331221 = 3 ⋅367110407.

It is a cyclic number.

It is not a de Polignac number, because 1221331011 - 2¹ = 1221331009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221331019) 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, 203555166 + ... + 203555171.

It is an arithmetic number, because the mean of its divisors is an integer number (407110338).

Almost surely, 2^1221331011 is an apocalyptic number.

1221331011 is a deficient number, since it is larger than the sum of its proper divisors (407110341).

1221331011 is an equidigital number, since it uses as much as digits as its factorization.

1221331011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407110340.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 1221331011 is about 34947.5465662470. The cubic root of 1221331011 is about 1068.9181749373.

Adding to 1221331011 its reverse (1101331221), we get a palindrome (2322662232).

The spelling of 1221331011 in words is "one billion, two hundred twenty-one million, three hundred thirty-one thousand, eleven".