216821880 has 128 divisors (see below), whose sum is σ = 788486400. Its totient is φ = 52560000.

The previous prime is 216821809. The next prime is 216821921. The reversal of 216821880 is 88128612.

216821880 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2755 + ... + 21005.

It is an arithmetic number, because the mean of its divisors is an integer number (6160050).

Almost surely, 2^216821880 is an apocalyptic number.

216821880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216821880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (394243200).

216821880 is an abundant number, since it is smaller than the sum of its proper divisors (571664520).

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

216821880 is a wasteful number, since it uses less digits than its factorization.

216821880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18282 (or 18272 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 36.

The square root of 216821880 is about 14724.8728347650. The cubic root of 216821880 is about 600.7600368335.

The spelling of 216821880 in words is "two hundred sixteen million, eight hundred twenty-one thousand, eight hundred eighty".