21121319987 has 2 divisors, whose sum is σ = 21121319988. Its totient is φ = 21121319986.

The previous prime is 21121319969. The next prime is 21121320001. The reversal of 21121319987 is 78991312112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21121319987 - 2¹⁴ = 21121303603 is a prime.

It is a super-2 number, since 2×21121319987² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121319917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560659993 + 10560659994.

It is an arithmetic number, because the mean of its divisors is an integer number (10560659994).

Almost surely, 2^21121319987 is an apocalyptic number.

21121319987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121319987 is an equidigital number, since it uses as much as digits as its factorization.

21121319987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 44.

The spelling of 21121319987 in words is "twenty-one billion, one hundred twenty-one million, three hundred nineteen thousand, nine hundred eighty-seven".