21391371869 has 16 divisors (see below), whose sum is σ = 24936960000. Its totient is φ = 17970956784.

The previous prime is 21391371851. The next prime is 21391371871. The reversal of 21391371869 is 96817319312.

It is a cyclic number.

It is not a de Polignac number, because 21391371869 - 2¹² = 21391367773 is a prime.

It is a super-2 number, since 2×21391371869² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21391371829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21269 + ... + 207930.

It is an arithmetic number, because the mean of its divisors is an integer number (1558560000).

Almost surely, 2^21391371869 is an apocalyptic number.

It is an amenable number.

21391371869 is a deficient number, since it is larger than the sum of its proper divisors (3545588131).

21391371869 is a wasteful number, since it uses less digits than its factorization.

21391371869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229472.

The product of its digits is 489888, while the sum is 50.

The spelling of 21391371869 in words is "twenty-one billion, three hundred ninety-one million, three hundred seventy-one thousand, eight hundred sixty-nine".