16557642546421 has 4 divisors (see below), whose sum is σ = 16626346457644. Its totient is φ = 16488938635200.

The previous prime is 16557642546377. The next prime is 16557642546563. The reversal of 16557642546421 is 12464524675561.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6099442787025 + 10458199759396 = 2469705^2 + 3233914^2 .

It is a cyclic number.

It is not a de Polignac number, because 16557642546421 - 2¹⁵ = 16557642513653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16557642546821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34351955250 + ... + 34351955731.

It is an arithmetic number, because the mean of its divisors is an integer number (4156586614411).

Almost surely, 2^{16557642546421} is an apocalyptic number.

It is an amenable number.

16557642546421 is a deficient number, since it is larger than the sum of its proper divisors (68703911223).

16557642546421 is an equidigital number, since it uses as much as digits as its factorization.

16557642546421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68703911222.

The product of its digits is 48384000, while the sum is 58.

The spelling of 16557642546421 in words is "sixteen trillion, five hundred fifty-seven billion, six hundred forty-two million, five hundred forty-six thousand, four hundred twenty-one".