20998618281 has 27 divisors (see below), whose sum is σ = 31513942551. Its totient is φ = 13991253768.

The previous prime is 20998618279. The next prime is 20998618301. The reversal of 20998618281 is 18281689902.

The square root of 20998618281 is 144909.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 19841257881 + 1157360400 = 140859^2 + 34020^2 .

It is a tau number, because it is divible by the number of its divisors (27).

It is not a de Polignac number, because 20998618281 - 2¹ = 20998618279 is a prime.

It is a super-2 number, since 2×20998618281² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20998618231) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 11736735 + ... + 11738523.

Almost surely, 2^20998618281 is an apocalyptic number.

20998618281 is the 144909-th square number.

20998618281 is the 72455-th centered octagonal number.

It is an amenable number.

20998618281 is a deficient number, since it is larger than the sum of its proper divisors (10515324270).

20998618281 is an frugal number, since it uses more digits than its factorization.

20998618281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3602 (or 1792 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 54.

The spelling of 20998618281 in words is "twenty billion, nine hundred ninety-eight million, six hundred eighteen thousand, two hundred eighty-one".