216655640 has 32 divisors (see below), whose sum is σ = 487918080. Its totient is φ = 86583552.

The previous prime is 216655619. The next prime is 216655657. The reversal of 216655640 is 46556612.

It is a self number, because there is not a number n which added to its sum of digits gives 216655640.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64892 + ... + 68148.

It is an arithmetic number, because the mean of its divisors is an integer number (15247440).

Almost surely, 2^216655640 is an apocalyptic number.

216655640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

216655640 is an abundant number, since it is smaller than the sum of its proper divisors (271262440).

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

216655640 is a wasteful number, since it uses less digits than its factorization.

216655640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4931 (or 4927 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The square root of 216655640 is about 14719.2268818712. The cubic root of 216655640 is about 600.6064608762.

The spelling of 216655640 in words is "two hundred sixteen million, six hundred fifty-five thousand, six hundred forty".