216254821 has 4 divisors (see below), whose sum is σ = 219800044. Its totient is φ = 212709600.

The previous prime is 216254777. The next prime is 216254839. The reversal of 216254821 is 128452612.

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 52056225 + 164198596 = 7215^2 + 12814^2 .

It is a cyclic number.

It is not a de Polignac number, because 216254821 - 2¹³ = 216246629 is a prime.

It is a super-2 number, since 2×216254821² = 93532295211484082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216254851) 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, 1772520 + ... + 1772641.

It is an arithmetic number, because the mean of its divisors is an integer number (54950011).

Almost surely, 2^216254821 is an apocalyptic number.

It is an amenable number.

216254821 is a deficient number, since it is larger than the sum of its proper divisors (3545223).

216254821 is an equidigital number, since it uses as much as digits as its factorization.

216254821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3545222.

The product of its digits is 7680, while the sum is 31.

The square root of 216254821 is about 14705.6050878568. The cubic root of 216254821 is about 600.2358526474.

The spelling of 216254821 in words is "two hundred sixteen million, two hundred fifty-four thousand, eight hundred twenty-one".