1211556985 has 8 divisors (see below), whose sum is σ = 1461901896. Its totient is φ = 963889920.

The previous prime is 1211556977. The next prime is 1211556991. The reversal of 1211556985 is 5896551121.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 128686336 + 1082870649 = 11344^2 + 32907^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1211556985 - 2³ = 1211556977 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 668464 + ... + 670273.

It is an arithmetic number, because the mean of its divisors is an integer number (182737737).

Almost surely, 2^1211556985 is an apocalyptic number.

It is an amenable number.

1211556985 is a deficient number, since it is larger than the sum of its proper divisors (250344911).

1211556985 is a wasteful number, since it uses less digits than its factorization.

1211556985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1338923.

The product of its digits is 108000, while the sum is 43.

The square root of 1211556985 is about 34807.4271528362. The cubic root of 1211556985 is about 1066.0591005605.

The spelling of 1211556985 in words is "one billion, two hundred eleven million, five hundred fifty-six thousand, nine hundred eighty-five".