216201978 has 24 divisors (see below), whose sum is σ = 488805408. Its totient is φ = 68933832.

The previous prime is 216201977. The next prime is 216202009. The reversal of 216201978 is 879102612.

216201978 is a `hidden beast` number, since 21 + 620 + 1 + 9 + 7 + 8 = 666.

It is a super-2 number, since 2×216201978² = 93486590582224968, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (216201977) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 260700 + ... + 261527.

It is an arithmetic number, because the mean of its divisors is an integer number (20366892).

Almost surely, 2^216201978 is an apocalyptic number.

216201978 is an abundant number, since it is smaller than the sum of its proper divisors (272603430).

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

216201978 is a wasteful number, since it uses less digits than its factorization.

216201978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 522258 (or 522255 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The square root of 216201978 is about 14703.8082822104. The cubic root of 216201978 is about 600.1869584049.

The spelling of 216201978 in words is "two hundred sixteen million, two hundred one thousand, nine hundred seventy-eight".