21021201221987 has 2 divisors, whose sum is σ = 21021201221988. Its totient is φ = 21021201221986.

The previous prime is 21021201221981. The next prime is 21021201222013. The reversal of 21021201221987 is 78912210212012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21021201221987 - 2³⁴ = 21004021352803 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21021201221987.

It is not a weakly prime, because it can be changed into another prime (21021201221981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510600610993 + 10510600610994.

It is an arithmetic number, because the mean of its divisors is an integer number (10510600610994).

Almost surely, 2^{21021201221987} is an apocalyptic number.

21021201221987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021201221987 is an equidigital number, since it uses as much as digits as its factorization.

21021201221987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 38.

Adding to 21021201221987 its reverse (78912210212012), we get a palindrome (99933411433999).

The spelling of 21021201221987 in words is "twenty-one trillion, twenty-one billion, two hundred one million, two hundred twenty-one thousand, nine hundred eighty-seven".