216581964 has 24 divisors (see below), whose sum is σ = 513644208. Its totient is φ = 71010240.

The previous prime is 216581957. The next prime is 216582011. The reversal of 216581964 is 469185612.

216581964 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 147207 + ... + 148670.

It is an arithmetic number, because the mean of its divisors is an integer number (21401842).

Almost surely, 2^216581964 is an apocalyptic number.

It is an amenable number.

216581964 is an abundant number, since it is smaller than the sum of its proper divisors (297062244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

216581964 is a wasteful number, since it uses less digits than its factorization.

216581964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295945 (or 295943 counting only the distinct ones).

The product of its digits is 103680, while the sum is 42.

The square root of 216581964 is about 14716.7239560984. The cubic root of 216581964 is about 600.5383723364.

The spelling of 216581964 in words is "two hundred sixteen million, five hundred eighty-one thousand, nine hundred sixty-four".