1213805851 has 4 divisors (see below), whose sum is σ = 1213879392. Its totient is φ = 1213732312.

The previous prime is 1213805833. The next prime is 1213805863. The reversal of 1213805851 is 1585083121.

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.

It is a cyclic number.

It is not a de Polignac number, because 1213805851 - 2⁵ = 1213805819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1213805881) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 750 + ... + 49276.

It is an arithmetic number, because the mean of its divisors is an integer number (303469848).

Almost surely, 2^1213805851 is an apocalyptic number.

1213805851 is a deficient number, since it is larger than the sum of its proper divisors (73541).

1213805851 is an equidigital number, since it uses as much as digits as its factorization.

1213805851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73540.

The product of its (nonzero) digits is 9600, while the sum is 34.

The square root of 1213805851 is about 34839.7165746221. The cubic root of 1213805851 is about 1066.7182915227.

Adding to 1213805851 its reverse (1585083121), we get a palindrome (2798888972).

The spelling of 1213805851 in words is "one billion, two hundred thirteen million, eight hundred five thousand, eight hundred fifty-one".