20647877309 has 2 divisors, whose sum is σ = 20647877310. Its totient is φ = 20647877308.

The previous prime is 20647877249. The next prime is 20647877317. The reversal of 20647877309 is 90377874602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20614642084 + 33235225 = 143578^2 + 5765^2 .

It is a cyclic number.

It is not a de Polignac number, because 20647877309 - 2⁸ = 20647877053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20647877339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10323938654 + 10323938655.

It is an arithmetic number, because the mean of its divisors is an integer number (10323938655).

Almost surely, 2^20647877309 is an apocalyptic number.

It is an amenable number.

20647877309 is a deficient number, since it is larger than the sum of its proper divisors (1).

20647877309 is an equidigital number, since it uses as much as digits as its factorization.

20647877309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3556224, while the sum is 53.

The spelling of 20647877309 in words is "twenty billion, six hundred forty-seven million, eight hundred seventy-seven thousand, three hundred nine".