13855206721 has 12 divisors (see below), whose sum is σ = 14357191212. Its totient is φ = 13370223104.

The previous prime is 13855206719. The next prime is 13855206749. The reversal of 13855206721 is 12760255831.

It can be written as a sum of positive squares in 6 ways, for example, as 453903025 + 13401303696 = 21305^2 + 115764^2 .

It is not a de Polignac number, because 13855206721 - 2¹ = 13855206719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13855209721) 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, 2211225 + ... + 2217481.

It is an arithmetic number, because the mean of its divisors is an integer number (1196432601).

Almost surely, 2^13855206721 is an apocalyptic number.

It is an amenable number.

13855206721 is a deficient number, since it is larger than the sum of its proper divisors (501984491).

13855206721 is an equidigital number, since it uses as much as digits as its factorization.

13855206721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8948 (or 8919 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 40.

The spelling of 13855206721 in words is "thirteen billion, eight hundred fifty-five million, two hundred six thousand, seven hundred twenty-one".