216665406136440 has 320 divisors, whose sum is σ = 732707692596000. Its totient is φ = 57423754662912.

The previous prime is 216665406136423. The next prime is 216665406136463. The reversal of 216665406136440 is 44631604566612.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 355995511 + ... + 356603609.

Almost surely, 2^{216665406136440} is an apocalyptic number.

216665406136440 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 216665406136440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (366353846298000).

216665406136440 is an abundant number, since it is smaller than the sum of its proper divisors (516042286459560).

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

216665406136440 is a wasteful number, since it uses less digits than its factorization.

216665406136440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 608796 (or 608783 counting only the distinct ones).

The product of its (nonzero) digits is 14929920, while the sum is 54.

The spelling of 216665406136440 in words is "two hundred sixteen trillion, six hundred sixty-five billion, four hundred six million, one hundred thirty-six thousand, four hundred forty".