20543543557 has 2 divisors, whose sum is σ = 20543543558. Its totient is φ = 20543543556.

The previous prime is 20543543491. The next prime is 20543543567. The reversal of 20543543557 is 75534534502.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18824114401 + 1719429156 = 137201^2 + 41466^2 .

It is a cyclic number.

It is not a de Polignac number, because 20543543557 - 2²⁷ = 20409325829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20543543567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10271771778 + 10271771779.

It is an arithmetic number, because the mean of its divisors is an integer number (10271771779).

Almost surely, 2^20543543557 is an apocalyptic number.

It is an amenable number.

20543543557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20543543557 is an equidigital number, since it uses as much as digits as its factorization.

20543543557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1260000, while the sum is 43.

The spelling of 20543543557 in words is "twenty billion, five hundred forty-three million, five hundred forty-three thousand, five hundred fifty-seven".