20956643 has 2 divisors, whose sum is σ = 20956644. Its totient is φ = 20956642.

The previous prime is 20956633. The next prime is 20956669. The reversal of 20956643 is 34665902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20956643 - 2⁴ = 20956627 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20956633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10478321 + 10478322.

It is an arithmetic number, because the mean of its divisors is an integer number (10478322).

Almost surely, 2^20956643 is an apocalyptic number.

20956643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20956643 is an equidigital number, since it uses as much as digits as its factorization.

20956643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 35.

The square root of 20956643 is about 4577.8426141579. The cubic root of 20956643 is about 275.7024159041.

The spelling of 20956643 in words is "twenty million, nine hundred fifty-six thousand, six hundred forty-three".