21711019897 has 4 divisors (see below), whose sum is σ = 24812594176. Its totient is φ = 18609445620.

The previous prime is 21711019879. The next prime is 21711019909. The reversal of 21711019897 is 79891011712.

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-21711019897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21711029897) 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, 1550787129 + ... + 1550787142.

It is an arithmetic number, because the mean of its divisors is an integer number (6203148544).

Almost surely, 2^21711019897 is an apocalyptic number.

It is an amenable number.

21711019897 is a deficient number, since it is larger than the sum of its proper divisors (3101574279).

21711019897 is an equidigital number, since it uses as much as digits as its factorization.

21711019897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3101574278.

The product of its (nonzero) digits is 63504, while the sum is 46.

The spelling of 21711019897 in words is "twenty-one billion, seven hundred eleven million, nineteen thousand, eight hundred ninety-seven".