20857715009 has 2 divisors, whose sum is σ = 20857715010. Its totient is φ = 20857715008.

The previous prime is 20857714991. The next prime is 20857715023. The reversal of 20857715009 is 90051775802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11587876609 + 9269838400 = 107647^2 + 96280^2 .

It is a cyclic number.

It is not a de Polignac number, because 20857715009 - 2⁸ = 20857714753 is a prime.

It is not a weakly prime, because it can be changed into another prime (20857715609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428857504 + 10428857505.

It is an arithmetic number, because the mean of its divisors is an integer number (10428857505).

Almost surely, 2^20857715009 is an apocalyptic number.

It is an amenable number.

20857715009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20857715009 is an equidigital number, since it uses as much as digits as its factorization.

20857715009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 176400, while the sum is 44.

The spelling of 20857715009 in words is "twenty billion, eight hundred fifty-seven million, seven hundred fifteen thousand, nine".