216677921 has 4 divisors (see below), whose sum is σ = 218911812. Its totient is φ = 214444032.

The previous prime is 216677911. The next prime is 216677927. The reversal of 216677921 is 129776612.

216677921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 87628321 + 129049600 = 9361^2 + 11360^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216677921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216677927) 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, 1116800 + ... + 1116993.

It is an arithmetic number, because the mean of its divisors is an integer number (54727953).

Almost surely, 2^216677921 is an apocalyptic number.

It is an amenable number.

216677921 is a deficient number, since it is larger than the sum of its proper divisors (2233891).

216677921 is an equidigital number, since it uses as much as digits as its factorization.

216677921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2233890.

The product of its digits is 63504, while the sum is 41.

The square root of 216677921 is about 14719.9837296106. The cubic root of 216677921 is about 600.6270490838.

The spelling of 216677921 in words is "two hundred sixteen million, six hundred seventy-seven thousand, nine hundred twenty-one".