21685464049 has 4 divisors (see below), whose sum is σ = 22628310336. Its totient is φ = 20742617764.

The previous prime is 21685464029. The next prime is 21685464079. The reversal of 21685464049 is 94046458612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21685464049 - 2⁹ = 21685463537 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21685463993 and 21685464011.

It is not an unprimeable number, because it can be changed into a prime (21685464029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 471423109 + ... + 471423154.

It is an arithmetic number, because the mean of its divisors is an integer number (5657077584).

Almost surely, 2^21685464049 is an apocalyptic number.

It is an amenable number.

21685464049 is a deficient number, since it is larger than the sum of its proper divisors (942846287).

21685464049 is an equidigital number, since it uses as much as digits as its factorization.

21685464049 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 942846286.

The product of its (nonzero) digits is 1658880, while the sum is 49.

The spelling of 21685464049 in words is "twenty-one billion, six hundred eighty-five million, four hundred sixty-four thousand, forty-nine".