21787826449 has 3 divisors (see below), whose sum is σ = 21787974057. Its totient is φ = 21787678842.

The previous prime is 21787826443. The next prime is 21787826491. The reversal of 21787826449 is 94462878712.

The square root of 21787826449 is 147607.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 21787826449 - 2¹⁵ = 21787793681 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21787826393 and 21787826402.

It is not an unprimeable number, because it can be changed into a prime (21787826443) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 73804 + ... + 221410.

It is an arithmetic number, because the mean of its divisors is an integer number (7262658019).

Almost surely, 2^21787826449 is an apocalyptic number.

21787826449 is the 147607-th square number.

21787826449 is the 73804-th centered octagonal number.

It is an amenable number.

21787826449 is a deficient number, since it is larger than the sum of its proper divisors (147608).

21787826449 is an frugal number, since it uses more digits than its factorization.

21787826449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295214 (or 147607 counting only the distinct ones).

The product of its digits is 10838016, while the sum is 58.

The spelling of 21787826449 in words is "twenty-one billion, seven hundred eighty-seven million, eight hundred twenty-six thousand, four hundred forty-nine".