15531391 has 2 divisors, whose sum is σ = 15531392. Its totient is φ = 15531390.

The previous prime is 15531389. The next prime is 15531401. The reversal of 15531391 is 19313551.

It is a weak prime.

It is an emirp because it is prime and its reverse (19313551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15531391 - 2¹ = 15531389 is a prime.

Together with 15531389, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15531311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7765695 + 7765696.

It is an arithmetic number, because the mean of its divisors is an integer number (7765696).

Almost surely, 2^15531391 is an apocalyptic number.

15531391 is the 2493-rd centered pentagonal number.

15531391 is a deficient number, since it is larger than the sum of its proper divisors (1).

15531391 is an equidigital number, since it uses as much as digits as its factorization.

15531391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2025, while the sum is 28.

The square root of 15531391 is about 3940.9885815617. The cubic root of 15531391 is about 249.4997516741.

The spelling of 15531391 in words is "fifteen million, five hundred thirty-one thousand, three hundred ninety-one".