20956321 has 2 divisors, whose sum is σ = 20956322. Its totient is φ = 20956320.

The previous prime is 20956307. The next prime is 20956333. The reversal of 20956321 is 12365902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18584721 + 2371600 = 4311^2 + 1540^2 .

It is a cyclic number.

It is not a de Polignac number, because 20956321 - 2¹³ = 20948129 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20956321.

It is not a weakly prime, because it can be changed into another prime (20956301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10478160 + 10478161.

It is an arithmetic number, because the mean of its divisors is an integer number (10478161).

Almost surely, 2^20956321 is an apocalyptic number.

It is an amenable number.

20956321 is a deficient number, since it is larger than the sum of its proper divisors (1).

20956321 is an equidigital number, since it uses as much as digits as its factorization.

20956321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 20956321 is about 4577.8074446180. The cubic root of 20956321 is about 275.7010038359.

The spelling of 20956321 in words is "twenty million, nine hundred fifty-six thousand, three hundred twenty-one".