216861940 has 24 divisors (see below), whose sum is σ = 475211520. Its totient is φ = 82973088.

The previous prime is 216861881. The next prime is 216861947. The reversal of 216861940 is 49168612.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 216861940.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216861947) 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, 235260 + ... + 236179.

It is an arithmetic number, because the mean of its divisors is an integer number (19800480).

Almost surely, 2^216861940 is an apocalyptic number.

216861940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

216861940 is an abundant number, since it is smaller than the sum of its proper divisors (258349580).

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

216861940 is a wasteful number, since it uses less digits than its factorization.

216861940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 471471 (or 471469 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 216861940 is about 14726.2330553336. The cubic root of 216861940 is about 600.7970333535.

The spelling of 216861940 in words is "two hundred sixteen million, eight hundred sixty-one thousand, nine hundred forty".