1221201311 has 4 divisors (see below), whose sum is σ = 1332219624. Its totient is φ = 1110183000.

The previous prime is 1221201301. The next prime is 1221201323. The reversal of 1221201311 is 1131021221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1131021221 = 11 ⋅102820111.

It is a cyclic number.

It is not a de Polignac number, because 1221201311 - 2¹⁴ = 1221184927 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 (1221201301) 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, 55509140 + ... + 55509161.

It is an arithmetic number, because the mean of its divisors is an integer number (333054906).

Almost surely, 2^1221201311 is an apocalyptic number.

1221201311 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1221201311 is a deficient number, since it is larger than the sum of its proper divisors (111018313).

1221201311 is a wasteful number, since it uses less digits than its factorization.

1221201311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111018312.

The product of its (nonzero) digits is 24, while the sum is 14.

The square root of 1221201311 is about 34945.6908788480. The cubic root of 1221201311 is about 1068.8803354562.

Adding to 1221201311 its reverse (1131021221), we get a palindrome (2352222532).

The spelling of 1221201311 in words is "one billion, two hundred twenty-one million, two hundred one thousand, three hundred eleven".