21535821812 has 12 divisors (see below), whose sum is σ = 37693659360. Its totient is φ = 10766204856.

The previous prime is 21535821793. The next prime is 21535821893. The reversal of 21535821812 is 21812853512.

It is a super-2 number, since 2×21535821812² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 397898 + ... + 448769.

It is an arithmetic number, because the mean of its divisors is an integer number (3141138280).

Almost surely, 2^21535821812 is an apocalyptic number.

It is an amenable number.

21535821812 is a deficient number, since it is larger than the sum of its proper divisors (16157837548).

21535821812 is a wasteful number, since it uses less digits than its factorization.

21535821812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 853030 (or 853028 counting only the distinct ones).

The product of its digits is 38400, while the sum is 38.

The spelling of 21535821812 in words is "twenty-one billion, five hundred thirty-five million, eight hundred twenty-one thousand, eight hundred twelve".