20543609 has 2 divisors, whose sum is σ = 20543610. Its totient is φ = 20543608.

The previous prime is 20543591. The next prime is 20543639. The reversal of 20543609 is 90634502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19333609 + 1210000 = 4397^2 + 1100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20543609 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20543639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10271804 + 10271805.

It is an arithmetic number, because the mean of its divisors is an integer number (10271805).

Almost surely, 2^20543609 is an apocalyptic number.

It is an amenable number.

20543609 is a deficient number, since it is larger than the sum of its proper divisors (1).

20543609 is an equidigital number, since it uses as much as digits as its factorization.

20543609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 20543609 is about 4532.5058190807. The cubic root of 20543609 is about 273.8791135625.

The spelling of 20543609 in words is "twenty million, five hundred forty-three thousand, six hundred nine".