216421251 has 8 divisors (see below), whose sum is σ = 296360784. Its totient is φ = 140381280.

The previous prime is 216421241. The next prime is 216421297. The reversal of 216421251 is 152124612.

216421251 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 216421251 - 2⁶ = 216421187 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216421241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 974760 + ... + 974981.

It is an arithmetic number, because the mean of its divisors is an integer number (37045098).

Almost surely, 2^216421251 is an apocalyptic number.

216421251 is a deficient number, since it is larger than the sum of its proper divisors (79939533).

216421251 is a wasteful number, since it uses less digits than its factorization.

216421251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1949781.

The product of its digits is 960, while the sum is 24.

The square root of 216421251 is about 14711.2627262244. The cubic root of 216421251 is about 600.3897939352.

Adding to 216421251 its reverse (152124612), we get a palindrome (368545863).

The spelling of 216421251 in words is "two hundred sixteen million, four hundred twenty-one thousand, two hundred fifty-one".