21056403349 has 4 divisors (see below), whose sum is σ = 21076250220. Its totient is φ = 21036556480.

The previous prime is 21056403343. The next prime is 21056403367. The reversal of 21056403349 is 94330465012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16752124900 + 4304278449 = 129430^2 + 65607^2 .

It is a cyclic number.

It is not a de Polignac number, because 21056403349 - 2¹⁵ = 21056370581 is a prime.

It is a super-3 number, since 3×21056403349³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056403343) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9921844 + ... + 9923965.

It is an arithmetic number, because the mean of its divisors is an integer number (5269062555).

Almost surely, 2^21056403349 is an apocalyptic number.

It is an amenable number.

21056403349 is a deficient number, since it is larger than the sum of its proper divisors (19846871).

21056403349 is a wasteful number, since it uses less digits than its factorization.

21056403349 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19846870.

The product of its (nonzero) digits is 77760, while the sum is 37.

The spelling of 21056403349 in words is "twenty-one billion, fifty-six million, four hundred three thousand, three hundred forty-nine".