1215391 has 2 divisors, whose sum is σ = 1215392. Its totient is φ = 1215390.

The previous prime is 1215367. The next prime is 1215397. The reversal of 1215391 is 1935121.

It is a strong prime.

It is an emirp because it is prime and its reverse (1935121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1215391 - 2⁵ = 1215359 is a prime.

It is equal to p₉₄₀₁₈ and since 1215391 and 94018 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1215397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607695 + 607696.

It is an arithmetic number, because the mean of its divisors is an integer number (607696).

2^1215391 is an apocalyptic number.

1215391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215391 is an equidigital number, since it uses as much as digits as its factorization.

1215391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 270, while the sum is 22.

The square root of 1215391 is about 1102.4477311873. The cubic root of 1215391 is about 106.7182443703.

Subtracting from 1215391 its product of digits (270), we obtain a palindrome (1215121).

The spelling of 1215391 in words is "one million, two hundred fifteen thousand, three hundred ninety-one".