21691313389 has 4 divisors (see below), whose sum is σ = 21747949056. Its totient is φ = 21634677724.

The previous prime is 21691313383. The next prime is 21691313411. The reversal of 21691313389 is 98331319612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21691313389 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 (21691313383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28317259 + ... + 28318024.

It is an arithmetic number, because the mean of its divisors is an integer number (5436987264).

Almost surely, 2^21691313389 is an apocalyptic number.

It is an amenable number.

21691313389 is a deficient number, since it is larger than the sum of its proper divisors (56635667).

21691313389 is an equidigital number, since it uses as much as digits as its factorization.

21691313389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56635666.

The product of its digits is 209952, while the sum is 46.

The spelling of 21691313389 in words is "twenty-one billion, six hundred ninety-one million, three hundred thirteen thousand, three hundred eighty-nine".