216129999 has 4 divisors (see below), whose sum is σ = 288173336. Its totient is φ = 144086664.

The previous prime is 216129989. The next prime is 216130009. The reversal of 216129999 is 999921612.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (216129989) and next prime (216130009).

It is not a de Polignac number, because 216129999 - 2¹⁶ = 216064463 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216129989) 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, 36021664 + ... + 36021669.

It is an arithmetic number, because the mean of its divisors is an integer number (72043334).

Almost surely, 2^216129999 is an apocalyptic number.

216129999 is a deficient number, since it is larger than the sum of its proper divisors (72043337).

216129999 is an equidigital number, since it uses as much as digits as its factorization.

216129999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72043336.

The product of its digits is 157464, while the sum is 48.

The square root of 216129999 is about 14701.3604472511. The cubic root of 216129999 is about 600.1203453045.

The spelling of 216129999 in words is "two hundred sixteen million, one hundred twenty-nine thousand, nine hundred ninety-nine".