215940247 has 2 divisors, whose sum is σ = 215940248. Its totient is φ = 215940246.

The previous prime is 215940233. The next prime is 215940271. The reversal of 215940247 is 742049512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215940247 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215940217) 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, 107970123 + 107970124.

It is an arithmetic number, because the mean of its divisors is an integer number (107970124).

Almost surely, 2^215940247 is an apocalyptic number.

215940247 is a deficient number, since it is larger than the sum of its proper divisors (1).

215940247 is an equidigital number, since it uses as much as digits as its factorization.

215940247 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 215940247 is about 14694.9054777498. The cubic root of 215940247 is about 599.9446680456.

Adding to 215940247 its reverse (742049512), we get a palindrome (957989759).

The spelling of 215940247 in words is "two hundred fifteen million, nine hundred forty thousand, two hundred forty-seven".