20515009 has 2 divisors, whose sum is σ = 20515010. Its totient is φ = 20515008.

The previous prime is 20515007. The next prime is 20515013. The reversal of 20515009 is 90051502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18249984 + 2265025 = 4272^2 + 1505^2 .

It is a cyclic number.

It is not a de Polignac number, because 20515009 - 2¹ = 20515007 is a prime.

Together with 20515007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20515007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10257504 + 10257505.

It is an arithmetic number, because the mean of its divisors is an integer number (10257505).

Almost surely, 2^20515009 is an apocalyptic number.

It is an amenable number.

20515009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20515009 is an equidigital number, since it uses as much as digits as its factorization.

20515009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 450, while the sum is 22.

The square root of 20515009 is about 4529.3497325775. The cubic root of 20515009 is about 273.7519599812.

The spelling of 20515009 in words is "twenty million, five hundred fifteen thousand, nine".