16505220217777 has 4 divisors (see below), whose sum is σ = 16505233207540. Its totient is φ = 16505207228016.

The previous prime is 16505220217729. The next prime is 16505220217817. The reversal of 16505220217777 is 77771202250561.

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 2665265214096 + 13839955003681 = 1632564^2 + 3720209^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16505220217777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16505220212777) 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, 4353618 + ... + 7208635.

It is an arithmetic number, because the mean of its divisors is an integer number (4126308301885).

Almost surely, 2^{16505220217777} is an apocalyptic number.

It is an amenable number.

16505220217777 is a deficient number, since it is larger than the sum of its proper divisors (12989763).

16505220217777 is a wasteful number, since it uses less digits than its factorization.

16505220217777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12989762.

The product of its (nonzero) digits is 2881200, while the sum is 52.

The spelling of 16505220217777 in words is "sixteen trillion, five hundred five billion, two hundred twenty million, two hundred seventeen thousand, seven hundred seventy-seven".