21791000121 has 8 divisors (see below), whose sum is σ = 31696000224. Its totient is φ = 13206666720.

The previous prime is 21791000081. The next prime is 21791000131. The reversal of 21791000121 is 12100019712.

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

It is not a de Polignac number, because 21791000121 - 2¹⁷ = 21790869049 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21791000091 and 21791000100.

It is not an unprimeable number, because it can be changed into a prime (21791000131) 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, 330166636 + ... + 330166701.

It is an arithmetic number, because the mean of its divisors is an integer number (3962000028).

Almost surely, 2^21791000121 is an apocalyptic number.

It is an amenable number.

21791000121 is a deficient number, since it is larger than the sum of its proper divisors (9905000103).

21791000121 is a wasteful number, since it uses less digits than its factorization.

21791000121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660333351.

The product of its (nonzero) digits is 252, while the sum is 24.

Adding to 21791000121 its reverse (12100019712), we get a palindrome (33891019833).

The spelling of 21791000121 in words is "twenty-one billion, seven hundred ninety-one million, one hundred twenty-one", and thus it is an aban number.