216121687 has 4 divisors (see below), whose sum is σ = 216919456. Its totient is φ = 215323920.

The previous prime is 216121681. The next prime is 216121691. The reversal of 216121687 is 786121612.

216121687 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 is a cyclic number.

It is not a de Polignac number, because 216121687 - 2³ = 216121679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216121681) 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, 398478 + ... + 399019.

It is an arithmetic number, because the mean of its divisors is an integer number (54229864).

Almost surely, 2^216121687 is an apocalyptic number.

216121687 is a deficient number, since it is larger than the sum of its proper divisors (797769).

216121687 is an equidigital number, since it uses as much as digits as its factorization.

216121687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 797768.

The product of its digits is 8064, while the sum is 34.

The square root of 216121687 is about 14701.0777496073. The cubic root of 216121687 is about 600.1126519960.

The spelling of 216121687 in words is "two hundred sixteen million, one hundred twenty-one thousand, six hundred eighty-seven".