21111020977 has 2 divisors, whose sum is σ = 21111020978. Its totient is φ = 21111020976.

The previous prime is 21111020969. The next prime is 21111021013. The reversal of 21111020977 is 77902011112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15398079921 + 5712941056 = 124089^2 + 75584^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111020977 - 2³ = 21111020969 is a prime.

It is not a weakly prime, because it can be changed into another prime (21111021977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555510488 + 10555510489.

It is an arithmetic number, because the mean of its divisors is an integer number (10555510489).

Almost surely, 2^21111020977 is an apocalyptic number.

It is an amenable number.

21111020977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111020977 is an equidigital number, since it uses as much as digits as its factorization.

21111020977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1764, while the sum is 31.

The spelling of 21111020977 in words is "twenty-one billion, one hundred eleven million, twenty thousand, nine hundred seventy-seven".