21665447995 has 8 divisors (see below), whose sum is σ = 26003780784. Its totient is φ = 17328862944.

The previous prime is 21665447987. The next prime is 21665448029. The reversal of 21665447995 is 59974456612.

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

It is a cyclic number.

It is not a de Polignac number, because 21665447995 - 2³ = 21665447987 is a prime.

It is a Duffinian 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, 409504 + ... + 459373.

It is an arithmetic number, because the mean of its divisors is an integer number (3250472598).

Almost surely, 2^21665447995 is an apocalyptic number.

21665447995 is a deficient number, since it is larger than the sum of its proper divisors (4338332789).

21665447995 is an equidigital number, since it uses as much as digits as its factorization.

21665447995 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 873869.

The product of its digits is 16329600, while the sum is 58.

The spelling of 21665447995 in words is "twenty-one billion, six hundred sixty-five million, four hundred forty-seven thousand, nine hundred ninety-five".