20720911 has 2 divisors, whose sum is σ = 20720912. Its totient is φ = 20720910.

The previous prime is 20720899. The next prime is 20720951. The reversal of 20720911 is 11902702.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20720911 - 2¹⁹ = 20196623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20720951) 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, 10360455 + 10360456.

It is an arithmetic number, because the mean of its divisors is an integer number (10360456).

Almost surely, 2^20720911 is an apocalyptic number.

20720911 is a deficient number, since it is larger than the sum of its proper divisors (1).

20720911 is an equidigital number, since it uses as much as digits as its factorization.

20720911 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 20720911 is about 4552.0227372016. The cubic root of 20720911 is about 274.6647639516.

The spelling of 20720911 in words is "twenty million, seven hundred twenty thousand, nine hundred eleven".