21012021011987 has 2 divisors, whose sum is σ = 21012021011988. Its totient is φ = 21012021011986.

The previous prime is 21012021011957. The next prime is 21012021012007. The reversal of 21012021011987 is 78911012021012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21012021011987 - 2²² = 21012016817683 is a prime.

It is not a weakly prime, because it can be changed into another prime (21012021011957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506010505993 + 10506010505994.

It is an arithmetic number, because the mean of its divisors is an integer number (10506010505994).

Almost surely, 2^{21012021011987} is an apocalyptic number.

21012021011987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012021011987 is an equidigital number, since it uses as much as digits as its factorization.

21012021011987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 35.

Adding to 21012021011987 its reverse (78911012021012), we get a palindrome (99923033032999).

The spelling of 21012021011987 in words is "twenty-one trillion, twelve billion, twenty-one million, eleven thousand, nine hundred eighty-seven".