20745649 has 2 divisors, whose sum is σ = 20745650. Its totient is φ = 20745648.

The previous prime is 20745629. The next prime is 20745667. The reversal of 20745649 is 94654702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15547249 + 5198400 = 3943^2 + 2280^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20745649 is a prime.

It is not a weakly prime, because it can be changed into another prime (20745629) 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, 10372824 + 10372825.

It is an arithmetic number, because the mean of its divisors is an integer number (10372825).

Almost surely, 2^20745649 is an apocalyptic number.

It is an amenable number.

20745649 is a deficient number, since it is larger than the sum of its proper divisors (1).

20745649 is an equidigital number, since it uses as much as digits as its factorization.

20745649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 37.

The square root of 20745649 is about 4554.7391802385. The cubic root of 20745649 is about 274.7740248291.

The spelling of 20745649 in words is "twenty million, seven hundred forty-five thousand, six hundred forty-nine".