20992381 has 2 divisors, whose sum is σ = 20992382. Its totient is φ = 20992380.

The previous prime is 20992379. The next prime is 20992393. The reversal of 20992381 is 18329902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15280281 + 5712100 = 3909^2 + 2390^2 .

It is a cyclic number.

It is not a de Polignac number, because 20992381 - 2¹ = 20992379 is a prime.

It is a super-2 number, since 2×20992381² = 881360120098322, which contains 22 as substring.

Together with 20992379, 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 (20992681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10496190 + 10496191.

It is an arithmetic number, because the mean of its divisors is an integer number (10496191).

Almost surely, 2^20992381 is an apocalyptic number.

It is an amenable number.

20992381 is a deficient number, since it is larger than the sum of its proper divisors (1).

20992381 is an equidigital number, since it uses as much as digits as its factorization.

20992381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 20992381 is about 4581.7443184883. The cubic root of 20992381 is about 275.8590481366.

The spelling of 20992381 in words is "twenty million, nine hundred ninety-two thousand, three hundred eighty-one".