1211351231 has 4 divisors (see below), whose sum is σ = 1211653872. Its totient is φ = 1211048592.

The previous prime is 1211351209. The next prime is 1211351233. The reversal of 1211351231 is 1321531121.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211351231 is a prime.

It is a super-2 number, since 2×1211351231² = 2934743609690430722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211351233) 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, 145235 + ... + 153348.

It is an arithmetic number, because the mean of its divisors is an integer number (302913468).

Almost surely, 2^1211351231 is an apocalyptic number.

1211351231 is a deficient number, since it is larger than the sum of its proper divisors (302641).

1211351231 is an equidigital number, since it uses as much as digits as its factorization.

1211351231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302640.

The product of its digits is 180, while the sum is 20.

The square root of 1211351231 is about 34804.4714225055. The cubic root of 1211351231 is about 1065.9987489235.

Adding to 1211351231 its reverse (1321531121), we get a palindrome (2532882352).

The spelling of 1211351231 in words is "one billion, two hundred eleven million, three hundred fifty-one thousand, two hundred thirty-one".