20702639 has 2 divisors, whose sum is σ = 20702640. Its totient is φ = 20702638.

The previous prime is 20702621. The next prime is 20702641. The reversal of 20702639 is 93620702.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20702639 is a prime.

Together with 20702641, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20702659) 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, 10351319 + 10351320.

It is an arithmetic number, because the mean of its divisors is an integer number (10351320).

Almost surely, 2^20702639 is an apocalyptic number.

20702639 is a deficient number, since it is larger than the sum of its proper divisors (1).

20702639 is an equidigital number, since it uses as much as digits as its factorization.

20702639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4536, while the sum is 29.

The square root of 20702639 is about 4550.0152746996. The cubic root of 20702639 is about 274.5840057509.

The spelling of 20702639 in words is "twenty million, seven hundred two thousand, six hundred thirty-nine".