21020020001977 has 2 divisors, whose sum is σ = 21020020001978. Its totient is φ = 21020020001976.

The previous prime is 21020020001927. The next prime is 21020020001989. The reversal of 21020020001977 is 77910002002012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11734707955216 + 9285312046761 = 3425596^2 + 3047181^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020020001977 - 2³¹ = 21017872518329 is a prime.

It is not a weakly prime, because it can be changed into another prime (21020020001927) 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, 10510010000988 + 10510010000989.

It is an arithmetic number, because the mean of its divisors is an integer number (10510010000989).

Almost surely, 2^{21020020001977} is an apocalyptic number.

It is an amenable number.

21020020001977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020020001977 is an equidigital number, since it uses as much as digits as its factorization.

21020020001977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3528, while the sum is 31.

Adding to 21020020001977 its reverse (77910002002012), we get a palindrome (98930022003989).

The spelling of 21020020001977 in words is "twenty-one trillion, twenty billion, twenty million, one thousand, nine hundred seventy-seven".