315821251 has 2 divisors, whose sum is σ = 315821252. Its totient is φ = 315821250.

The previous prime is 315821227. The next prime is 315821267. The reversal of 315821251 is 152128513.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-315821251 is a prime.

It is not a weakly prime, because it can be changed into another prime (315821201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 157910625 + 157910626.

It is an arithmetic number, because the mean of its divisors is an integer number (157910626).

Almost surely, 2^315821251 is an apocalyptic number.

315821251 is a deficient number, since it is larger than the sum of its proper divisors (1).

315821251 is an equidigital number, since it uses as much as digits as its factorization.

315821251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2400, while the sum is 28.

The square root of 315821251 is about 17771.3604150048. The cubic root of 315821251 is about 681.0000071876. Note that the first 5 decimals are identical.

Adding to 315821251 its reverse (152128513), we get a palindrome (467949764).

The spelling of 315821251 in words is "three hundred fifteen million, eight hundred twenty-one thousand, two hundred fifty-one".