20851728551 has 2 divisors, whose sum is σ = 20851728552. Its totient is φ = 20851728550.

The previous prime is 20851728497. The next prime is 20851728571. The reversal of 20851728551 is 15582715802.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20851728551 - 2³⁰ = 19777986727 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20851728571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10425864275 + 10425864276.

It is an arithmetic number, because the mean of its divisors is an integer number (10425864276).

Almost surely, 2^20851728551 is an apocalyptic number.

20851728551 is a deficient number, since it is larger than the sum of its proper divisors (1).

20851728551 is an equidigital number, since it uses as much as digits as its factorization.

20851728551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224000, while the sum is 44.

The spelling of 20851728551 in words is "twenty billion, eight hundred fifty-one million, seven hundred twenty-eight thousand, five hundred fifty-one".