21056392898 has 6 divisors (see below), whose sum is σ = 31584897171. Its totient is φ = 10528093842.

The previous prime is 21056392891. The next prime is 21056392921. The reversal of 21056392898 is 89829365012.

It can be written as a sum of positive squares in only one way, i.e., 10528196449 + 10528196449 = 102607^2 + 102607^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=102607.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21056392891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 153911 + ... + 256517.

Almost surely, 2^21056392898 is an apocalyptic number.

21056392898 is a deficient number, since it is larger than the sum of its proper divisors (10528504273).

21056392898 is an frugal number, since it uses more digits than its factorization.

21056392898 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205216 (or 102609 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 53.

The spelling of 21056392898 in words is "twenty-one billion, fifty-six million, three hundred ninety-two thousand, eight hundred ninety-eight".