20668541 has 2 divisors, whose sum is σ = 20668542. Its totient is φ = 20668540.

The previous prime is 20668519. The next prime is 20668553. The reversal of 20668541 is 14586602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10562500 + 10106041 = 3250^2 + 3179^2 .

It is a cyclic number.

It is not a de Polignac number, because 20668541 - 2⁶ = 20668477 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20668498 and 20668507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20668511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10334270 + 10334271.

It is an arithmetic number, because the mean of its divisors is an integer number (10334271).

Almost surely, 2^20668541 is an apocalyptic number.

It is an amenable number.

20668541 is a deficient number, since it is larger than the sum of its proper divisors (1).

20668541 is an equidigital number, since it uses as much as digits as its factorization.

20668541 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 32.

The square root of 20668541 is about 4546.2667101700. The cubic root of 20668541 is about 274.4331729608.

The spelling of 20668541 in words is "twenty million, six hundred sixty-eight thousand, five hundred forty-one".