20720549 has 2 divisors, whose sum is σ = 20720550. Its totient is φ = 20720548.

The previous prime is 20720543. The next prime is 20720551. The reversal of 20720549 is 94502702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20205025 + 515524 = 4495^2 + 718^2 .

It is a cyclic number.

It is not a de Polignac number, because 20720549 - 2⁴ = 20720533 is a prime.

It is a super-2 number, since 2×20720549² = 858682301722802, which contains 22 as substring.

Together with 20720551, 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 (20720543) 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, 10360274 + 10360275.

It is an arithmetic number, because the mean of its divisors is an integer number (10360275).

Almost surely, 2^20720549 is an apocalyptic number.

It is an amenable number.

20720549 is a deficient number, since it is larger than the sum of its proper divisors (1).

20720549 is an equidigital number, since it uses as much as digits as its factorization.

20720549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 20720549 is about 4551.9829744849. The cubic root of 20720549 is about 274.6631644527.

The spelling of 20720549 in words is "twenty million, seven hundred twenty thousand, five hundred forty-nine".