21115728691394 has 8 divisors (see below), whose sum is σ = 31673612784060. Its totient is φ = 10557857763376.

The previous prime is 21115728691301. The next prime is 21115728691399. The reversal of 21115728691394 is 49319682751112.

It can be written as a sum of positive squares in 2 ways, for example, as 19474242439369 + 1641486252025 = 4412963^2 + 1281205^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21115728691399) 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, 3628412 + ... + 7442904.

Almost surely, 2^{21115728691394} is an apocalyptic number.

21115728691394 is a deficient number, since it is larger than the sum of its proper divisors (10557884092666).

21115728691394 is a wasteful number, since it uses less digits than its factorization.

21115728691394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6582324.

The product of its digits is 6531840, while the sum is 59.

The spelling of 21115728691394 in words is "twenty-one trillion, one hundred fifteen billion, seven hundred twenty-eight million, six hundred ninety-one thousand, three hundred ninety-four".