21212118027787 has 2 divisors, whose sum is σ = 21212118027788. Its totient is φ = 21212118027786.

The previous prime is 21212118027767. The next prime is 21212118027803. The reversal of 21212118027787 is 78772081121212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212118027787 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212118027787.

It is not a weakly prime, because it can be changed into another prime (21212118027767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606059013893 + 10606059013894.

It is an arithmetic number, because the mean of its divisors is an integer number (10606059013894).

Almost surely, 2^{21212118027787} is an apocalyptic number.

21212118027787 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212118027787 is an equidigital number, since it uses as much as digits as its factorization.

21212118027787 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 351232, while the sum is 49.

Adding to 21212118027787 its reverse (78772081121212), we get a palindrome (99984199148999).

The spelling of 21212118027787 in words is "twenty-one trillion, two hundred twelve billion, one hundred eighteen million, twenty-seven thousand, seven hundred eighty-seven".