20891240447 has 8 divisors (see below), whose sum is σ = 26046221952. Its totient is φ = 16278888600.

The previous prime is 20891240441. The next prime is 20891240501. The reversal of 20891240447 is 74404219802.

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

It is a cyclic number.

It is not a de Polignac number, because 20891240447 - 2⁸ = 20891240191 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 (20891240441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135657329 + ... + 135657482.

It is an arithmetic number, because the mean of its divisors is an integer number (3255777744).

Almost surely, 2^20891240447 is an apocalyptic number.

20891240447 is a deficient number, since it is larger than the sum of its proper divisors (5154981505).

20891240447 is a wasteful number, since it uses less digits than its factorization.

20891240447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271314829.

The product of its (nonzero) digits is 129024, while the sum is 41.

The spelling of 20891240447 in words is "twenty billion, eight hundred ninety-one million, two hundred forty thousand, four hundred forty-seven".