20543313991 has 4 divisors (see below), whose sum is σ = 20592343800. Its totient is φ = 20494284184.

The previous prime is 20543313977. The next prime is 20543314013. The reversal of 20543313991 is 19931334502.

It is a happy number.

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 20543313991 - 2²⁵ = 20509759559 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 (20543313691) 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, 24514276 + ... + 24515113.

It is an arithmetic number, because the mean of its divisors is an integer number (5148085950).

Almost surely, 2^20543313991 is an apocalyptic number.

20543313991 is a deficient number, since it is larger than the sum of its proper divisors (49029809).

20543313991 is an equidigital number, since it uses as much as digits as its factorization.

20543313991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49029808.

The product of its (nonzero) digits is 87480, while the sum is 40.

The spelling of 20543313991 in words is "twenty billion, five hundred forty-three million, three hundred thirteen thousand, nine hundred ninety-one".