216535665640 has 64 divisors (see below), whose sum is σ = 556847026560. Its totient is φ = 74235329280.

The previous prime is 216535665637. The next prime is 216535665653. The reversal of 216535665640 is 46566535612.

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, 6224134 + ... + 6258826.

It is an arithmetic number, because the mean of its divisors is an integer number (8700734790).

Almost surely, 2^216535665640 is an apocalyptic number.

216535665640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

216535665640 is an abundant number, since it is smaller than the sum of its proper divisors (340311360920).

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

216535665640 is a wasteful number, since it uses less digits than its factorization.

216535665640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57002 (or 56998 counting only the distinct ones).

The product of its (nonzero) digits is 3888000, while the sum is 49.

The spelling of 216535665640 in words is "two hundred sixteen billion, five hundred thirty-five million, six hundred sixty-five thousand, six hundred forty".