216639940 has 48 divisors (see below), whose sum is σ = 500157504. Its totient is φ = 78166400.

The previous prime is 216639937. The next prime is 216639953. The reversal of 216639940 is 49936612.

216639940 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 216639893 and 216639902.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25062 + ... + 32578.

It is an arithmetic number, because the mean of its divisors is an integer number (10419948).

Almost surely, 2^216639940 is an apocalyptic number.

216639940 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 216639940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (250078752).

216639940 is an abundant number, since it is smaller than the sum of its proper divisors (283517564).

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

216639940 is a wasteful number, since it uses less digits than its factorization.

216639940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7668 (or 7666 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 216639940 is about 14718.6935561550. The cubic root of 216639940 is about 600.5919528314.

The spelling of 216639940 in words is "two hundred sixteen million, six hundred thirty-nine thousand, nine hundred forty".