21665415782 has 8 divisors (see below), whose sum is σ = 32863271400. Its totient is φ = 10710991984.

The previous prime is 21665415781. The next prime is 21665415851. The reversal of 21665415782 is 28751456612.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665415781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60857732 + ... + 60858087.

It is an arithmetic number, because the mean of its divisors is an integer number (4107908925).

Almost surely, 2^21665415782 is an apocalyptic number.

21665415782 is a deficient number, since it is larger than the sum of its proper divisors (11197855618).

21665415782 is a wasteful number, since it uses less digits than its factorization.

21665415782 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121715910.

The product of its digits is 806400, while the sum is 47.

The spelling of 21665415782 in words is "twenty-one billion, six hundred sixty-five million, four hundred fifteen thousand, seven hundred eighty-two".