20947739 has 2 divisors, whose sum is σ = 20947740. Its totient is φ = 20947738.

The previous prime is 20947727. The next prime is 20947741. The reversal of 20947739 is 93774902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20947739 - 2¹⁶ = 20882203 is a prime.

It is a Sophie Germain prime.

Together with 20947741, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20947696 and 20947705.

It is not a weakly prime, because it can be changed into another prime (20947799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10473869 + 10473870.

It is an arithmetic number, because the mean of its divisors is an integer number (10473870).

Almost surely, 2^20947739 is an apocalyptic number.

20947739 is a deficient number, since it is larger than the sum of its proper divisors (1).

20947739 is an equidigital number, since it uses as much as digits as its factorization.

20947739 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 95256, while the sum is 41.

The square root of 20947739 is about 4576.8700003387. The cubic root of 20947739 is about 275.6633638151.

The spelling of 20947739 in words is "twenty million, nine hundred forty-seven thousand, seven hundred thirty-nine".