216978664 has 24 divisors (see below), whose sum is σ = 473257890. Its totient is φ = 92990688.

The previous prime is 216978653. The next prime is 216978679. The reversal of 216978664 is 466879612.

It can be written as a sum of positive squares in only one way, i.e., 133402500 + 83576164 = 11550^2 + 9142^2 .

It is a Harshad number since it is a multiple of its sum of digits (49).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 276367 + ... + 277150.

Almost surely, 2^216978664 is an apocalyptic number.

It is an amenable number.

216978664 is an abundant number, since it is smaller than the sum of its proper divisors (256279226).

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

216978664 is a wasteful number, since it uses less digits than its factorization.

216978664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 553537 (or 553526 counting only the distinct ones).

The product of its digits is 870912, while the sum is 49.

The square root of 216978664 is about 14730.1956538262. The cubic root of 216978664 is about 600.9048052303.

The spelling of 216978664 in words is "two hundred sixteen million, nine hundred seventy-eight thousand, six hundred sixty-four".