501681809 has 2 divisors, whose sum is σ = 501681810. Its totient is φ = 501681808.

The previous prime is 501681707. The next prime is 501681823. The reversal of 501681809 is 908186105.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 485100625 + 16581184 = 22025^2 + 4072^2 .

It is a cyclic number.

It is not a de Polignac number, because 501681809 - 2¹² = 501677713 is a prime.

It is a Chen prime.

It is equal to p_26439545 and since 501681809 and 26439545 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (501681839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 250840904 + 250840905.

It is an arithmetic number, because the mean of its divisors is an integer number (250840905).

Almost surely, 2^501681809 is an apocalyptic number.

It is an amenable number.

501681809 is a deficient number, since it is larger than the sum of its proper divisors (1).

501681809 is an equidigital number, since it uses as much as digits as its factorization.

501681809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 38.

The square root of 501681809 is about 22398.2545971779. The cubic root of 501681809 is about 794.5894318731.

The spelling of 501681809 in words is "five hundred one million, six hundred eighty-one thousand, eight hundred nine".