1213171787 has 4 divisors (see below), whose sum is σ = 1213250016. Its totient is φ = 1213093560.

The previous prime is 1213171783. The next prime is 1213171789. The reversal of 1213171787 is 7871713121.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 7871713121 = 9437 ⋅834133.

It is a cyclic number.

It is not a de Polignac number, because 1213171787 - 2² = 1213171783 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1213171787.

It is not an unprimeable number, because it can be changed into a prime (1213171783) 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 3 ways as a sum of consecutive naturals, for example, 7139 + ... + 49772.

It is an arithmetic number, because the mean of its divisors is an integer number (303312504).

Almost surely, 2^1213171787 is an apocalyptic number.

1213171787 is a deficient number, since it is larger than the sum of its proper divisors (78229).

1213171787 is an equidigital number, since it uses as much as digits as its factorization.

1213171787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78228.

The product of its digits is 16464, while the sum is 38.

The square root of 1213171787 is about 34830.6156563446. The cubic root of 1213171787 is about 1066.5325162129.

The spelling of 1213171787 in words is "one billion, two hundred thirteen million, one hundred seventy-one thousand, seven hundred eighty-seven".