20989523813 has 4 divisors (see below), whose sum is σ = 21014904960. Its totient is φ = 20964142668.

The previous prime is 20989523759. The next prime is 20989523831. The reversal of 20989523813 is 31832598902.

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 not a de Polignac number, because 20989523813 - 2¹⁸ = 20989261669 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 (20989523213) 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, 12689333 + ... + 12690986.

It is an arithmetic number, because the mean of its divisors is an integer number (5253726240).

Almost surely, 2^20989523813 is an apocalyptic number.

It is an amenable number.

20989523813 is a deficient number, since it is larger than the sum of its proper divisors (25381147).

20989523813 is an equidigital number, since it uses as much as digits as its factorization.

20989523813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25381146.

The product of its (nonzero) digits is 933120, while the sum is 50.

The spelling of 20989523813 in words is "twenty billion, nine hundred eighty-nine million, five hundred twenty-three thousand, eight hundred thirteen".