21133253421 has 24 divisors (see below), whose sum is σ = 34969945920. Its totient is φ = 12047308416.

The previous prime is 21133253417. The next prime is 21133253437. The reversal of 21133253421 is 12435233112.

21133253421 is a `hidden beast` number, since 211 + 3 + 3 + 25 + 3 + 421 = 666.

It is not a de Polignac number, because 21133253421 - 2² = 21133253417 is a prime.

It is a super-2 number, since 2×21133253421² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21133253411) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 373900 + ... + 426693.

It is an arithmetic number, because the mean of its divisors is an integer number (1457081080).

Almost surely, 2^21133253421 is an apocalyptic number.

21133253421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21133253421 is a deficient number, since it is larger than the sum of its proper divisors (13836692499).

21133253421 is a wasteful number, since it uses less digits than its factorization.

21133253421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801025 (or 801022 counting only the distinct ones).

The product of its digits is 4320, while the sum is 27.

Adding to 21133253421 its reverse (12435233112), we get a palindrome (33568486533).

The spelling of 21133253421 in words is "twenty-one billion, one hundred thirty-three million, two hundred fifty-three thousand, four hundred twenty-one".