21598334881 has 2 divisors, whose sum is σ = 21598334882. Its totient is φ = 21598334880.

The previous prime is 21598334867. The next prime is 21598334899. The reversal of 21598334881 is 18843389512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20266084881 + 1332250000 = 142359^2 + 36500^2 .

It is a cyclic number.

It is not a de Polignac number, because 21598334881 - 2¹⁹ = 21597810593 is a prime.

It is a super-4 number, since 4×21598334881⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (21598332881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10799167440 + 10799167441.

It is an arithmetic number, because the mean of its divisors is an integer number (10799167441).

Almost surely, 2^21598334881 is an apocalyptic number.

It is an amenable number.

21598334881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21598334881 is an equidigital number, since it uses as much as digits as its factorization.

21598334881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1658880, while the sum is 52.

The spelling of 21598334881 in words is "twenty-one billion, five hundred ninety-eight million, three hundred thirty-four thousand, eight hundred eighty-one".