21256080289 has 4 divisors (see below), whose sum is σ = 21256647300. Its totient is φ = 21255513280.

The previous prime is 21256080281. The next prime is 21256080301. The reversal of 21256080289 is 98208065212.

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 20849049664 + 407030625 = 144392^2 + 20175^2 .

It is a cyclic number.

It is not a de Polignac number, because 21256080289 - 2³ = 21256080281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21256080281) 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, 222964 + ... + 303685.

It is an arithmetic number, because the mean of its divisors is an integer number (5314161825).

Almost surely, 2^21256080289 is an apocalyptic number.

It is an amenable number.

21256080289 is a deficient number, since it is larger than the sum of its proper divisors (567011).

21256080289 is an equidigital number, since it uses as much as digits as its factorization.

21256080289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567010.

The product of its (nonzero) digits is 138240, while the sum is 43.

The spelling of 21256080289 in words is "twenty-one billion, two hundred fifty-six million, eighty thousand, two hundred eighty-nine".