1212987905 has 4 divisors (see below), whose sum is σ = 1455585492. Its totient is φ = 970390320.

The previous prime is 1212987889. The next prime is 1212987907. The reversal of 1212987905 is 5097892121.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 141800464 + 1071187441 = 11908^2 + 32729^2 .

It is not a de Polignac number, because 1212987905 - 2⁴ = 1212987889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1212987907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121298786 + ... + 121298795.

It is an arithmetic number, because the mean of its divisors is an integer number (363896373).

Almost surely, 2^1212987905 is an apocalyptic number.

It is an amenable number.

1212987905 is a deficient number, since it is larger than the sum of its proper divisors (242597587).

1212987905 is an equidigital number, since it uses as much as digits as its factorization.

1212987905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242597586.

The product of its (nonzero) digits is 90720, while the sum is 44.

The square root of 1212987905 is about 34827.9758958226. The cubic root of 1212987905 is about 1066.4786282575.

The spelling of 1212987905 in words is "one billion, two hundred twelve million, nine hundred eighty-seven thousand, nine hundred five".