1211605831 has 2 divisors, whose sum is σ = 1211605832. Its totient is φ = 1211605830.

The previous prime is 1211605817. The next prime is 1211605847. The reversal of 1211605831 is 1385061121.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211605831 is a prime.

It is a super-2 number, since 2×1211605831² = 2935977379426401122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1211605831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211605231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605802915 + 605802916.

It is an arithmetic number, because the mean of its divisors is an integer number (605802916).

Almost surely, 2^1211605831 is an apocalyptic number.

1211605831 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211605831 is an equidigital number, since it uses as much as digits as its factorization.

1211605831 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 1211605831 is about 34808.1288063579. The cubic root of 1211605831 is about 1066.0734270356.

Adding to 1211605831 its reverse (1385061121), we get a palindrome (2596666952).

The spelling of 1211605831 in words is "one billion, two hundred eleven million, six hundred five thousand, eight hundred thirty-one".