21791066789 has 8 divisors (see below), whose sum is σ = 21864924408. Its totient is φ = 21717305280.

The previous prime is 21791066723. The next prime is 21791066821. The reversal of 21791066789 is 98766019712.

It can be written as a sum of positive squares in 4 ways, for example, as 6721540225 + 15069526564 = 81985^2 + 122758^2 .

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-21791066789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21791062789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 445619 + ... + 492095.

It is an arithmetic number, because the mean of its divisors is an integer number (2733115551).

Almost surely, 2^21791066789 is an apocalyptic number.

It is an amenable number.

21791066789 is a deficient number, since it is larger than the sum of its proper divisors (73857619).

21791066789 is a wasteful number, since it uses less digits than its factorization.

21791066789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48055.

The product of its (nonzero) digits is 2286144, while the sum is 56.

The spelling of 21791066789 in words is "twenty-one billion, seven hundred ninety-one million, sixty-six thousand, seven hundred eighty-nine".