21002100020987 has 2 divisors, whose sum is σ = 21002100020988. Its totient is φ = 21002100020986.

The previous prime is 21002100020971. The next prime is 21002100021047. The reversal of 21002100020987 is 78902000120012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21002100020987 - 2⁴ = 21002100020971 is a prime.

It is not a weakly prime, because it can be changed into another prime (21002100020927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501050010493 + 10501050010494.

It is an arithmetic number, because the mean of its divisors is an integer number (10501050010494).

Almost surely, 2^{21002100020987} is an apocalyptic number.

21002100020987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002100020987 is an equidigital number, since it uses as much as digits as its factorization.

21002100020987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 32.

Adding to 21002100020987 its reverse (78902000120012), we get a palindrome (99904100140999).

The spelling of 21002100020987 in words is "twenty-one trillion, two billion, one hundred million, twenty thousand, nine hundred eighty-seven".