21308103881 has 2 divisors, whose sum is σ = 21308103882. Its totient is φ = 21308103880.

The previous prime is 21308103871. The next prime is 21308103893. The reversal of 21308103881 is 18830180312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20942720656 + 365383225 = 144716^2 + 19115^2 .

It is a cyclic number.

It is not a de Polignac number, because 21308103881 - 2¹⁰ = 21308102857 is a prime.

It is a super-2 number, since 2×21308103881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21308103851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10654051940 + 10654051941.

It is an arithmetic number, because the mean of its divisors is an integer number (10654051941).

Almost surely, 2^21308103881 is an apocalyptic number.

It is an amenable number.

21308103881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21308103881 is an equidigital number, since it uses as much as digits as its factorization.

21308103881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 35.

The spelling of 21308103881 in words is "twenty-one billion, three hundred eight million, one hundred three thousand, eight hundred eighty-one".