20956399 has 2 divisors, whose sum is σ = 20956400. Its totient is φ = 20956398.

The previous prime is 20956391. The next prime is 20956423. The reversal of 20956399 is 99365902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20956399 - 2³ = 20956391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20956391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10478199 + 10478200.

It is an arithmetic number, because the mean of its divisors is an integer number (10478200).

Almost surely, 2^20956399 is an apocalyptic number.

20956399 is a deficient number, since it is larger than the sum of its proper divisors (1).

20956399 is an equidigital number, since it uses as much as digits as its factorization.

20956399 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 131220, while the sum is 43.

The square root of 20956399 is about 4577.8159639723. The cubic root of 20956399 is about 275.7013458910.

The spelling of 20956399 in words is "twenty million, nine hundred fifty-six thousand, three hundred ninety-nine".