16777020221 has 12 divisors (see below), whose sum is σ = 18188187732. Its totient is φ = 15468276096.

The previous prime is 16777020179. The next prime is 16777020257. The reversal of 16777020221 is 12202077761.

It can be written as a sum of positive squares in 6 ways, for example, as 632522500 + 16144497721 = 25150^2 + 127061^2 .

It is a de Polignac number, because none of the positive numbers 2^k-16777020221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16777020721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 86915 + ... + 202751.

It is an arithmetic number, because the mean of its divisors is an integer number (1515682311).

Almost surely, 2^16777020221 is an apocalyptic number.

It is an amenable number.

16777020221 is a deficient number, since it is larger than the sum of its proper divisors (1411167511).

16777020221 is a wasteful number, since it uses less digits than its factorization.

16777020221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116720 (or 116707 counting only the distinct ones).

The product of its (nonzero) digits is 16464, while the sum is 35.

Adding to 16777020221 its reverse (12202077761), we get a palindrome (28979097982).

The spelling of 16777020221 in words is "sixteen billion, seven hundred seventy-seven million, twenty thousand, two hundred twenty-one".