21428064193 has 4 divisors (see below), whose sum is σ = 21428842708. Its totient is φ = 21427285680.

The previous prime is 21428064181. The next prime is 21428064209. The reversal of 21428064193 is 39146082412.

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 6653175489 + 14774888704 = 81567^2 + 121552^2 .

It is a cyclic number.

It is not a de Polignac number, because 21428064193 - 2²¹ = 21425967041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21428064113) 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, 346398 + ... + 403543.

It is an arithmetic number, because the mean of its divisors is an integer number (5357210677).

Almost surely, 2^21428064193 is an apocalyptic number.

It is an amenable number.

21428064193 is a deficient number, since it is larger than the sum of its proper divisors (778515).

21428064193 is an equidigital number, since it uses as much as digits as its factorization.

21428064193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778514.

The product of its (nonzero) digits is 82944, while the sum is 40.

The spelling of 21428064193 in words is "twenty-one billion, four hundred twenty-eight million, sixty-four thousand, one hundred ninety-three".