215861929091 has 2 divisors, whose sum is σ = 215861929092. Its totient is φ = 215861929090.

The previous prime is 215861929069. The next prime is 215861929093. The reversal of 215861929091 is 190929168512.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215861929091 is a prime.

Together with 215861929093, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (215861929093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107930964545 + 107930964546.

It is an arithmetic number, because the mean of its divisors is an integer number (107930964546).

Almost surely, 2^215861929091 is an apocalyptic number.

215861929091 is a deficient number, since it is larger than the sum of its proper divisors (1).

215861929091 is an equidigital number, since it uses as much as digits as its factorization.

215861929091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 699840, while the sum is 53.

The spelling of 215861929091 in words is "two hundred fifteen billion, eight hundred sixty-one million, nine hundred twenty-nine thousand, ninety-one".