21051816533 has 16 divisors (see below), whose sum is σ = 25373782656. Its totient is φ = 17229104640.

The previous prime is 21051816521. The next prime is 21051816553. The reversal of 21051816533 is 33561815012.

It is not a de Polignac number, because 21051816533 - 2⁸ = 21051816277 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21051816493 and 21051816502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051816553) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2443016 + ... + 2451617.

It is an arithmetic number, because the mean of its divisors is an integer number (1585861416).

Almost surely, 2^21051816533 is an apocalyptic number.

21051816533 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21051816533 is a deficient number, since it is larger than the sum of its proper divisors (4321966123).

21051816533 is a wasteful number, since it uses less digits than its factorization.

21051816533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4894684.

The product of its (nonzero) digits is 21600, while the sum is 35.

The spelling of 21051816533 in words is "twenty-one billion, fifty-one million, eight hundred sixteen thousand, five hundred thirty-three".