1213255391 has 4 divisors (see below), whose sum is σ = 1216561632. Its totient is φ = 1209949152.

The previous prime is 1213255369. The next prime is 1213255399. The reversal of 1213255391 is 1935523121.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1213255391 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 (1213255399) 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, 1652570 + ... + 1653303.

It is an arithmetic number, because the mean of its divisors is an integer number (304140408).

Almost surely, 2^1213255391 is an apocalyptic number.

1213255391 is a deficient number, since it is larger than the sum of its proper divisors (3306241).

1213255391 is an equidigital number, since it uses as much as digits as its factorization.

1213255391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3306240.

The product of its digits is 8100, while the sum is 32.

The square root of 1213255391 is about 34831.8157867200. The cubic root of 1213255391 is about 1066.5570151715.

The spelling of 1213255391 in words is "one billion, two hundred thirteen million, two hundred fifty-five thousand, three hundred ninety-one".