21420754849 has 8 divisors (see below), whose sum is σ = 23077437992. Its totient is φ = 19765347840.

The previous prime is 21420754843. The next prime is 21420754867. The reversal of 21420754849 is 94845702412.

It can be written as a sum of positive squares in 4 ways, for example, as 2885838400 + 18534916449 = 53720^2 + 136143^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21420754849 - 2⁷ = 21420754721 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21420754799 and 21420754808.

It is not an unprimeable number, because it can be changed into a prime (21420754843) 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 7 ways as a sum of consecutive naturals, for example, 284022 + ... + 351439.

It is an arithmetic number, because the mean of its divisors is an integer number (2884679749).

Almost surely, 2^21420754849 is an apocalyptic number.

It is an amenable number.

21420754849 is a deficient number, since it is larger than the sum of its proper divisors (1656683143).

21420754849 is a wasteful number, since it uses less digits than its factorization.

21420754849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 638067.

The product of its (nonzero) digits is 645120, while the sum is 46.

The spelling of 21420754849 in words is "twenty-one billion, four hundred twenty million, seven hundred fifty-four thousand, eight hundred forty-nine".