21356433 has 16 divisors (see below), whose sum is σ = 36159360. Its totient is φ = 12203568.

The previous prime is 21356431. The next prime is 21356453. The reversal of 21356433 is 33465312.

It is a happy number.

21356433 is a `hidden beast` number, since 2 + 13 + 5 + 643 + 3 = 666.

It is not a de Polignac number, because 21356433 - 2¹ = 21356431 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21356397 and 21356406.

It is not an unprimeable number, because it can be changed into a prime (21356431) 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, 56310 + ... + 56687.

It is an arithmetic number, because the mean of its divisors is an integer number (2259960).

Almost surely, 2^21356433 is an apocalyptic number.

It is an amenable number.

21356433 is a deficient number, since it is larger than the sum of its proper divisors (14802927).

21356433 is a wasteful number, since it uses less digits than its factorization.

21356433 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113013 (or 113007 counting only the distinct ones).

The product of its digits is 6480, while the sum is 27.

The square root of 21356433 is about 4621.3020892385. The cubic root of 21356433 is about 277.4445762212. Note that the first 3 decimals are identical.

The spelling of 21356433 in words is "twenty-one million, three hundred fifty-six thousand, four hundred thirty-three".