21011219987 has 2 divisors, whose sum is σ = 21011219988. Its totient is φ = 21011219986.

The previous prime is 21011219909. The next prime is 21011220019. The reversal of 21011219987 is 78991211012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21011219987 - 2¹⁸ = 21010957843 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011219687) 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, 10505609993 + 10505609994.

It is an arithmetic number, because the mean of its divisors is an integer number (10505609994).

Almost surely, 2^21011219987 is an apocalyptic number.

21011219987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011219987 is an equidigital number, since it uses as much as digits as its factorization.

21011219987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 41.

The spelling of 21011219987 in words is "twenty-one billion, eleven million, two hundred nineteen thousand, nine hundred eighty-seven".