22391981 has 2 divisors, whose sum is σ = 22391982. Its totient is φ = 22391980.

The previous prime is 22391969. The next prime is 22391983. The reversal of 22391981 is 18919322.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17147881 + 5244100 = 4141^2 + 2290^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-22391981 is a prime.

It is a super-2 number, since 2×22391981² = 1002801626208722, which contains 22 as substring.

Together with 22391983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (22391983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11195990 + 11195991.

It is an arithmetic number, because the mean of its divisors is an integer number (11195991).

Almost surely, 2^22391981 is an apocalyptic number.

It is an amenable number.

22391981 is a deficient number, since it is larger than the sum of its proper divisors (1).

22391981 is an equidigital number, since it uses as much as digits as its factorization.

22391981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 35.

The square root of 22391981 is about 4732.0165891510. The cubic root of 22391981 is about 281.8583070007.

The spelling of 22391981 in words is "twenty-two million, three hundred ninety-one thousand, nine hundred eighty-one".