20851257543 has 4 divisors (see below), whose sum is σ = 27801676728. Its totient is φ = 13900838360.

The previous prime is 20851257527. The next prime is 20851257563. The reversal of 20851257543 is 34575215802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20851257543 - 2⁴ = 20851257527 is a prime.

It is a super-2 number, since 2×20851257543² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20851257495 and 20851257504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20851257523) 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 in 3 ways as a sum of consecutive naturals, for example, 3475209588 + ... + 3475209593.

It is an arithmetic number, because the mean of its divisors is an integer number (6950419182).

Almost surely, 2^20851257543 is an apocalyptic number.

20851257543 is a deficient number, since it is larger than the sum of its proper divisors (6950419185).

20851257543 is an equidigital number, since it uses as much as digits as its factorization.

20851257543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6950419184.

The product of its (nonzero) digits is 336000, while the sum is 42.

The spelling of 20851257543 in words is "twenty billion, eight hundred fifty-one million, two hundred fifty-seven thousand, five hundred forty-three".