16477721217521 has 4 divisors (see below), whose sum is σ = 16477860933492. Its totient is φ = 16477581501552.

The previous prime is 16477721217511. The next prime is 16477721217539. The reversal of 16477721217521 is 12571212777461.

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 9421897779121 + 7055823438400 = 3069511^2 + 2656280^2 .

It is a cyclic number.

It is not a de Polignac number, because 16477721217521 - 2⁶ = 16477721217457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16477721217511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 69680930 + ... + 69917003.

It is an arithmetic number, because the mean of its divisors is an integer number (4119465233373).

Almost surely, 2^{16477721217521} is an apocalyptic number.

It is an amenable number.

16477721217521 is a deficient number, since it is larger than the sum of its proper divisors (139715971).

16477721217521 is a wasteful number, since it uses less digits than its factorization.

16477721217521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139715970.

The product of its digits is 2304960, while the sum is 53.

The spelling of 16477721217521 in words is "sixteen trillion, four hundred seventy-seven billion, seven hundred twenty-one million, two hundred seventeen thousand, five hundred twenty-one".