21201029981 has 2 divisors, whose sum is σ = 21201029982. Its totient is φ = 21201029980.

The previous prime is 21201029963. The next prime is 21201030077. The reversal of 21201029981 is 18992010212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16984605625 + 4216424356 = 130325^2 + 64934^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201029981 - 2¹⁸ = 21200767837 is a prime.

It is a super-2 number, since 2×21201029981² (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 (21201029081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600514990 + 10600514991.

It is an arithmetic number, because the mean of its divisors is an integer number (10600514991).

Almost surely, 2^21201029981 is an apocalyptic number.

It is an amenable number.

21201029981 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201029981 is an equidigital number, since it uses as much as digits as its factorization.

21201029981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 35.

The spelling of 21201029981 in words is "twenty-one billion, two hundred one million, twenty-nine thousand, nine hundred eighty-one".