20897218789 has 4 divisors (see below), whose sum is σ = 21462008524. Its totient is φ = 20332429056.

The previous prime is 20897218759. The next prime is 20897218817. The reversal of 20897218789 is 98781279802.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20259252225 + 637966564 = 142335^2 + 25258^2 .

It is a cyclic number.

It is not a de Polignac number, because 20897218789 - 2¹³ = 20897210597 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 (20897218709) 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, 282394812 + ... + 282394885.

It is an arithmetic number, because the mean of its divisors is an integer number (5365502131).

Almost surely, 2^20897218789 is an apocalyptic number.

It is an amenable number.

20897218789 is a deficient number, since it is larger than the sum of its proper divisors (564789735).

20897218789 is an equidigital number, since it uses as much as digits as its factorization.

20897218789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 564789734.

The product of its (nonzero) digits is 8128512, while the sum is 61.

The spelling of 20897218789 in words is "twenty billion, eight hundred ninety-seven million, two hundred eighteen thousand, seven hundred eighty-nine".