216655115721 has 16 divisors (see below), whose sum is σ = 315653910528. Its totient is φ = 131089798800.

The previous prime is 216655115689. The next prime is 216655115723. The reversal of 216655115721 is 127511556612.

It is a happy number.

It is not a de Polignac number, because 216655115721 - 2⁵ = 216655115689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216655115723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5387965 + ... + 5428026.

It is an arithmetic number, because the mean of its divisors is an integer number (19728369408).

Almost surely, 2^216655115721 is an apocalyptic number.

It is an amenable number.

216655115721 is a deficient number, since it is larger than the sum of its proper divisors (98998794807).

216655115721 is a wasteful number, since it uses less digits than its factorization.

216655115721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10816612.

The product of its digits is 126000, while the sum is 42.

The spelling of 216655115721 in words is "two hundred sixteen billion, six hundred fifty-five million, one hundred fifteen thousand, seven hundred twenty-one".