21021020999977 has 2 divisors, whose sum is σ = 21021020999978. Its totient is φ = 21021020999976.

The previous prime is 21021020999959. The next prime is 21021021000047. The reversal of 21021020999977 is 77999902012012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20984424927376 + 36596072601 = 4580876^2 + 191301^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021020999977 - 2³⁹ = 20471265186089 is a prime.

It is not a weakly prime, because it can be changed into another prime (21021020999477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510510499988 + 10510510499989.

It is an arithmetic number, because the mean of its divisors is an integer number (10510510499989).

Almost surely, 2^{21021020999977} is an apocalyptic number.

It is an amenable number.

21021020999977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021020999977 is an equidigital number, since it uses as much as digits as its factorization.

21021020999977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2571912, while the sum is 58.

The spelling of 21021020999977 in words is "twenty-one trillion, twenty-one billion, twenty million, nine hundred ninety-nine thousand, nine hundred seventy-seven".