215687971 has 2 divisors, whose sum is σ = 215687972. Its totient is φ = 215687970.

The previous prime is 215687881. The next prime is 215687977. The reversal of 215687971 is 179786512.

It is a happy number.

215687971 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 215687971 - 2¹¹ = 215685923 is a prime.

It is not a weakly prime, because it can be changed into another prime (215687977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107843985 + 107843986.

It is an arithmetic number, because the mean of its divisors is an integer number (107843986).

Almost surely, 2^215687971 is an apocalyptic number.

215687971 is a deficient number, since it is larger than the sum of its proper divisors (1).

215687971 is an equidigital number, since it uses as much as digits as its factorization.

215687971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 211680, while the sum is 46.

The square root of 215687971 is about 14686.3191780650. The cubic root of 215687971 is about 599.7109450270.

The spelling of 215687971 in words is "two hundred fifteen million, six hundred eighty-seven thousand, nine hundred seventy-one".