216621455 has 4 divisors (see below), whose sum is σ = 259945752. Its totient is φ = 173297160.

The previous prime is 216621443. The next prime is 216621473. The reversal of 216621455 is 554126612.

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

It is not a de Polignac number, because 216621455 - 2⁴ = 216621439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21662141 + ... + 21662150.

It is an arithmetic number, because the mean of its divisors is an integer number (64986438).

Almost surely, 2^216621455 is an apocalyptic number.

216621455 is a deficient number, since it is larger than the sum of its proper divisors (43324297).

216621455 is an equidigital number, since it uses as much as digits as its factorization.

216621455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43324296.

The product of its digits is 14400, while the sum is 32.

The square root of 216621455 is about 14718.0655997995. The cubic root of 216621455 is about 600.5748703272.

The spelling of 216621455 in words is "two hundred sixteen million, six hundred twenty-one thousand, four hundred fifty-five".