20993981449 has 15 divisors (see below), whose sum is σ = 24499806407. Its totient is φ = 17988755736.

The previous prime is 20993981441. The next prime is 20993981473. The reversal of 20993981449 is 94418939902.

The square root of 20993981449 is 144893.

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., 3903125625 + 17090855824 = 62475^2 + 130732^2 .

It is not a de Polignac number, because 20993981449 - 2³ = 20993981441 is a prime.

It is a super-2 number, since 2×20993981449² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20993981393 and 20993981402.

It is not an unprimeable number, because it can be changed into a prime (20993981441) 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 14 ways as a sum of consecutive naturals, for example, 7098279 + ... + 7101235.

Almost surely, 2^20993981449 is an apocalyptic number.

20993981449 is the 144893-rd square number.

20993981449 is the 72447-th centered octagonal number.

It is an amenable number.

20993981449 is a deficient number, since it is larger than the sum of its proper divisors (3505824958).

20993981449 is an frugal number, since it uses more digits than its factorization.

20993981449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5942 (or 2964 counting only the distinct ones).

The product of its (nonzero) digits is 5038848, while the sum is 58.

The spelling of 20993981449 in words is "twenty billion, nine hundred ninety-three million, nine hundred eighty-one thousand, four hundred forty-nine".