21200109977 has 2 divisors, whose sum is σ = 21200109978. Its totient is φ = 21200109976.

The previous prime is 21200109967. The next prime is 21200110021. The reversal of 21200109977 is 77990100212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17841212041 + 3358897936 = 133571^2 + 57956^2 .

It is a cyclic number.

It is not a de Polignac number, because 21200109977 - 2³⁴ = 4020240793 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21200109977.

It is not a weakly prime, because it can be changed into another prime (21200109937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600054988 + 10600054989.

It is an arithmetic number, because the mean of its divisors is an integer number (10600054989).

Almost surely, 2^21200109977 is an apocalyptic number.

It is an amenable number.

21200109977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21200109977 is an equidigital number, since it uses as much as digits as its factorization.

21200109977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15876, while the sum is 38.

The spelling of 21200109977 in words is "twenty-one billion, two hundred million, one hundred nine thousand, nine hundred seventy-seven".