21121815874 has 8 divisors (see below), whose sum is σ = 31693213440. Its totient is φ = 10557411396.

The previous prime is 21121815857. The next prime is 21121815887. The reversal of 21121815874 is 47851812112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21121815874² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1740714 + ... + 1752805.

It is an arithmetic number, because the mean of its divisors is an integer number (3961651680).

Almost surely, 2^21121815874 is an apocalyptic number.

21121815874 is a deficient number, since it is larger than the sum of its proper divisors (10571397566).

21121815874 is a wasteful number, since it uses less digits than its factorization.

21121815874 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3496544.

The product of its digits is 35840, while the sum is 40.

The spelling of 21121815874 in words is "twenty-one billion, one hundred twenty-one million, eight hundred fifteen thousand, eight hundred seventy-four".