21905284031977 has 2 divisors, whose sum is σ = 21905284031978. Its totient is φ = 21905284031976.

The previous prime is 21905284031941. The next prime is 21905284032029. The reversal of 21905284031977 is 77913048250912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13166999220496 + 8738284811481 = 3628636^2 + 2956059^2 .

It is a cyclic number.

It is not a de Polignac number, because 21905284031977 - 2¹¹ = 21905284029929 is a prime.

It is not a weakly prime, because it can be changed into another prime (21905284031077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10952642015988 + 10952642015989.

It is an arithmetic number, because the mean of its divisors is an integer number (10952642015989).

Almost surely, 2^{21905284031977} is an apocalyptic number.

It is an amenable number.

21905284031977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21905284031977 is an equidigital number, since it uses as much as digits as its factorization.

21905284031977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7620480, while the sum is 58.

The spelling of 21905284031977 in words is "twenty-one trillion, nine hundred five billion, two hundred eighty-four million, thirty-one thousand, nine hundred seventy-seven".