21293679091 has 4 divisors (see below), whose sum is σ = 21296105712. Its totient is φ = 21291252472.

The previous prime is 21293679089. The next prime is 21293679119. The reversal of 21293679091 is 19097639212.

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 21293679091 - 2¹ = 21293679089 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21293679041) 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, 1200100 + ... + 1217713.

It is an arithmetic number, because the mean of its divisors is an integer number (5324026428).

Almost surely, 2^21293679091 is an apocalyptic number.

21293679091 is a deficient number, since it is larger than the sum of its proper divisors (2426621).

21293679091 is an equidigital number, since it uses as much as digits as its factorization.

21293679091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2426620.

The product of its (nonzero) digits is 367416, while the sum is 49.

The spelling of 21293679091 in words is "twenty-one billion, two hundred ninety-three million, six hundred seventy-nine thousand, ninety-one".