15318421 has 2 divisors, whose sum is σ = 15318422. Its totient is φ = 15318420.

The previous prime is 15318419. The next prime is 15318451. The reversal of 15318421 is 12481351.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15295921 + 22500 = 3911^2 + 150^2 .

It is an emirp because it is prime and its reverse (12481351) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15318421 - 2¹ = 15318419 is a prime.

Together with 15318419, 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 (15318451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7659210 + 7659211.

It is an arithmetic number, because the mean of its divisors is an integer number (7659211).

Almost surely, 2^15318421 is an apocalyptic number.

It is an amenable number.

15318421 is a deficient number, since it is larger than the sum of its proper divisors (1).

15318421 is an equidigital number, since it uses as much as digits as its factorization.

15318421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 25.

The square root of 15318421 is about 3913.8754451311. The cubic root of 15318421 is about 248.3540998304.

Adding to 15318421 its reverse (12481351), we get a palindrome (27799772).

The spelling of 15318421 in words is "fifteen million, three hundred eighteen thousand, four hundred twenty-one".