21011321211977 has 2 divisors, whose sum is σ = 21011321211978. Its totient is φ = 21011321211976.

The previous prime is 21011321211949. The next prime is 21011321212009. The reversal of 21011321211977 is 77911212311012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17127173973001 + 3884147238976 = 4138499^2 + 1970824^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011321211977 - 2²⁸ = 21011052776521 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011321211977.

It is not a weakly prime, because it can be changed into another prime (21011321211277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505660605988 + 10505660605989.

It is an arithmetic number, because the mean of its divisors is an integer number (10505660605989).

Almost surely, 2^{21011321211977} is an apocalyptic number.

It is an amenable number.

21011321211977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011321211977 is an equidigital number, since it uses as much as digits as its factorization.

21011321211977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10584, while the sum is 38.

Adding to 21011321211977 its reverse (77911212311012), we get a palindrome (98922533522989).

The spelling of 21011321211977 in words is "twenty-one trillion, eleven billion, three hundred twenty-one million, two hundred eleven thousand, nine hundred seventy-seven".