20021021201977 has 2 divisors, whose sum is σ = 20021021201978. Its totient is φ = 20021021201976.

The previous prime is 20021021201903. The next prime is 20021021202043. The reversal of 20021021201977 is 77910212012002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17057403863721 + 2963617338256 = 4130061^2 + 1721516^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20021021201977 is a prime.

It is not a weakly prime, because it can be changed into another prime (20021021202977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010510600988 + 10010510600989.

It is an arithmetic number, because the mean of its divisors is an integer number (10010510600989).

Almost surely, 2^{20021021201977} is an apocalyptic number.

It is an amenable number.

20021021201977 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021021201977 is an equidigital number, since it uses as much as digits as its factorization.

20021021201977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 34.

Adding to 20021021201977 its reverse (77910212012002), we get a palindrome (97931233213979).

The spelling of 20021021201977 in words is "twenty trillion, twenty-one billion, twenty-one million, two hundred one thousand, nine hundred seventy-seven".