20408491009 has 2 divisors, whose sum is σ = 20408491010. Its totient is φ = 20408491008.

The previous prime is 20408490931. The next prime is 20408491013. The reversal of 20408491009 is 90019480402.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11076931009 + 9331560000 = 105247^2 + 96600^2 .

It is a cyclic number.

It is not a de Polignac number, because 20408491009 - 2¹³ = 20408482817 is a prime.

It is not a weakly prime, because it can be changed into another prime (20408491099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10204245504 + 10204245505.

It is an arithmetic number, because the mean of its divisors is an integer number (10204245505).

Almost surely, 2^20408491009 is an apocalyptic number.

It is an amenable number.

20408491009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20408491009 is an equidigital number, since it uses as much as digits as its factorization.

20408491009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 37.

The spelling of 20408491009 in words is "twenty billion, four hundred eight million, four hundred ninety-one thousand, nine".