216621651 has 4 divisors (see below), whose sum is σ = 288828872. Its totient is φ = 144414432.

The previous prime is 216621623. The next prime is 216621689. The reversal of 216621651 is 156126612.

216621651 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 not a de Polignac number, because 216621651 - 2¹¹ = 216619603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216626651) 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, 36103606 + ... + 36103611.

It is an arithmetic number, because the mean of its divisors is an integer number (72207218).

Almost surely, 2^216621651 is an apocalyptic number.

216621651 is a deficient number, since it is larger than the sum of its proper divisors (72207221).

216621651 is an equidigital number, since it uses as much as digits as its factorization.

216621651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72207220.

The product of its digits is 4320, while the sum is 30.

The square root of 216621651 is about 14718.0722582817. The cubic root of 216621651 is about 600.5750514614.

The spelling of 216621651 in words is "two hundred sixteen million, six hundred twenty-one thousand, six hundred fifty-one".