20211320981 has 2 divisors, whose sum is σ = 20211320982. Its totient is φ = 20211320980.

The previous prime is 20211320963. The next prime is 20211320999. The reversal of 20211320981 is 18902311202.

It is a balanced prime because it is at equal distance from previous prime (20211320963) and next prime (20211320999).

It can be written as a sum of positive squares in only one way, i.e., 19219385956 + 991935025 = 138634^2 + 31495^2 .

It is a cyclic number.

It is not a de Polignac number, because 20211320981 - 2¹⁸ = 20211058837 is a prime.

It is a super-2 number, since 2×20211320981² (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 (20211323981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10105660490 + 10105660491.

It is an arithmetic number, because the mean of its divisors is an integer number (10105660491).

Almost surely, 2^20211320981 is an apocalyptic number.

It is an amenable number.

20211320981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20211320981 is an equidigital number, since it uses as much as digits as its factorization.

20211320981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 29.

The spelling of 20211320981 in words is "twenty billion, two hundred eleven million, three hundred twenty thousand, nine hundred eighty-one".