21103333981 has 2 divisors, whose sum is σ = 21103333982. Its totient is φ = 21103333980.

The previous prime is 21103333973. The next prime is 21103334009. The reversal of 21103333981 is 18933330112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18423718756 + 2679615225 = 135734^2 + 51765^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103333981 - 2³ = 21103333973 is a prime.

It is a super-2 number, since 2×21103333981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21103330981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551666990 + 10551666991.

It is an arithmetic number, because the mean of its divisors is an integer number (10551666991).

Almost surely, 2^21103333981 is an apocalyptic number.

It is an amenable number.

21103333981 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103333981 is an equidigital number, since it uses as much as digits as its factorization.

21103333981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 34.

The spelling of 21103333981 in words is "twenty-one billion, one hundred three million, three hundred thirty-three thousand, nine hundred eighty-one".