21297891683 has 4 divisors (see below), whose sum is σ = 21315194208. Its totient is φ = 21280589160.

The previous prime is 21297891679. The next prime is 21297891691. The reversal of 21297891683 is 38619879212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21297891683 - 2² = 21297891679 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21297891613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8649416 + ... + 8651877.

It is an arithmetic number, because the mean of its divisors is an integer number (5328798552).

Almost surely, 2^21297891683 is an apocalyptic number.

21297891683 is a deficient number, since it is larger than the sum of its proper divisors (17302525).

21297891683 is a wasteful number, since it uses less digits than its factorization.

21297891683 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17302524.

The product of its digits is 2612736, while the sum is 56.

The spelling of 21297891683 in words is "twenty-one billion, two hundred ninety-seven million, eight hundred ninety-one thousand, six hundred eighty-three".