22081981 has 2 divisors, whose sum is σ = 22081982. Its totient is φ = 22081980.

The previous prime is 22081979. The next prime is 22081991. The reversal of 22081981 is 18918022.

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., 20025625 + 2056356 = 4475^2 + 1434^2 .

It is a cyclic number.

It is not a de Polignac number, because 22081981 - 2¹ = 22081979 is a prime.

It is a super-2 number, since 2×22081981² = 975227769768722, which contains 22 as substring.

Together with 22081979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (22081921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11040990 + 11040991.

It is an arithmetic number, because the mean of its divisors is an integer number (11040991).

Almost surely, 2^22081981 is an apocalyptic number.

It is an amenable number.

22081981 is a deficient number, since it is larger than the sum of its proper divisors (1).

22081981 is an equidigital number, since it uses as much as digits as its factorization.

22081981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 22081981 is about 4699.1468374589. The cubic root of 22081981 is about 280.5515531254.

It can be divided in two parts, 220819 and 81, that added together give a square (220900 = 470²).

The spelling of 22081981 in words is "twenty-two million, eighty-one thousand, nine hundred eighty-one".