1211957989 has 16 divisors (see below), whose sum is σ = 1366272000. Its totient is φ = 1065078000.

The previous prime is 1211957983. The next prime is 1211957993. The reversal of 1211957989 is 9897591121.

It is a cyclic number.

It is not a de Polignac number, because 1211957989 - 2⁹ = 1211957477 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 (1211957983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 509974 + ... + 512344.

It is an arithmetic number, because the mean of its divisors is an integer number (85392000).

Almost surely, 2^1211957989 is an apocalyptic number.

It is an amenable number.

1211957989 is a deficient number, since it is larger than the sum of its proper divisors (154314011).

1211957989 is a wasteful number, since it uses less digits than its factorization.

1211957989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3912.

The product of its digits is 408240, while the sum is 52.

The square root of 1211957989 is about 34813.1869986073. The cubic root of 1211957989 is about 1066.1767031752.

The spelling of 1211957989 in words is "one billion, two hundred eleven million, nine hundred fifty-seven thousand, nine hundred eighty-nine".