21798153505 has 4 divisors (see below), whose sum is σ = 26157784212. Its totient is φ = 17438522800.

The previous prime is 21798153499. The next prime is 21798153523. The reversal of 21798153505 is 50535189712.

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 17320402449 + 4477751056 = 131607^2 + 66916^2 .

It is not a de Polignac number, because 21798153505 - 2¹⁵ = 21798120737 is a prime.

It is a Duffinian number.

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, 2179815346 + ... + 2179815355.

It is an arithmetic number, because the mean of its divisors is an integer number (6539446053).

Almost surely, 2^21798153505 is an apocalyptic number.

It is an amenable number.

21798153505 is a deficient number, since it is larger than the sum of its proper divisors (4359630707).

21798153505 is an equidigital number, since it uses as much as digits as its factorization.

21798153505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4359630706.

The product of its (nonzero) digits is 378000, while the sum is 46.

The spelling of 21798153505 in words is "twenty-one billion, seven hundred ninety-eight million, one hundred fifty-three thousand, five hundred five".