21216780372787 has 8 divisors (see below), whose sum is σ = 21950599878000. Its totient is φ = 20483107960224.

The previous prime is 21216780372769. The next prime is 21216780372833. The reversal of 21216780372787 is 78727308761212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21216780372787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21216780372737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36479653 + ... + 37056694.

It is an arithmetic number, because the mean of its divisors is an integer number (2743824984750).

Almost surely, 2^{21216780372787} is an apocalyptic number.

21216780372787 is a deficient number, since it is larger than the sum of its proper divisors (733819505213).

21216780372787 is an equidigital number, since it uses as much as digits as its factorization.

21216780372787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73546325.

The product of its (nonzero) digits is 22127616, while the sum is 61.

The spelling of 21216780372787 in words is "twenty-one trillion, two hundred sixteen billion, seven hundred eighty million, three hundred seventy-two thousand, seven hundred eighty-seven".