216921284 has 6 divisors (see below), whose sum is σ = 379612254. Its totient is φ = 108460640.

The previous prime is 216921251. The next prime is 216921301. The reversal of 216921284 is 482129612.

It can be written as a sum of positive squares in only one way, i.e., 119464900 + 97456384 = 10930^2 + 9872^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27115157 + ... + 27115164.

It is an arithmetic number, because the mean of its divisors is an integer number (63268709).

Almost surely, 2^216921284 is an apocalyptic number.

It is an amenable number.

216921284 is a deficient number, since it is larger than the sum of its proper divisors (162690970).

216921284 is a wasteful number, since it uses less digits than its factorization.

216921284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54230325 (or 54230323 counting only the distinct ones).

The product of its digits is 13824, while the sum is 35.

The square root of 216921284 is about 14728.2478251827. The cubic root of 216921284 is about 600.8518308089.

The spelling of 216921284 in words is "two hundred sixteen million, nine hundred twenty-one thousand, two hundred eighty-four".