20720789 has 2 divisors, whose sum is σ = 20720790. Its totient is φ = 20720788.

The previous prime is 20720771. The next prime is 20720893. The reversal of 20720789 is 98702702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20340100 + 380689 = 4510^2 + 617^2 .

It is a cyclic number.

It is not a de Polignac number, because 20720789 - 2⁸ = 20720533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20720719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10360394 + 10360395.

It is an arithmetic number, because the mean of its divisors is an integer number (10360395).

Almost surely, 2^20720789 is an apocalyptic number.

It is an amenable number.

20720789 is a deficient number, since it is larger than the sum of its proper divisors (1).

20720789 is an equidigital number, since it uses as much as digits as its factorization.

20720789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14112, while the sum is 35.

The square root of 20720789 is about 4552.0093365458. The cubic root of 20720789 is about 274.6642248961.

The spelling of 20720789 in words is "twenty million, seven hundred twenty thousand, seven hundred eighty-nine".