21433821 has 8 divisors (see below), whose sum is σ = 30259584. Its totient is φ = 13448640.

The previous prime is 21433771. The next prime is 21433831. The reversal of 21433821 is 12833412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21433821 - 2¹⁴ = 21417437 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21433791 and 21433800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21433831) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 210085 + ... + 210186.

It is an arithmetic number, because the mean of its divisors is an integer number (3782448).

Almost surely, 2^21433821 is an apocalyptic number.

It is an amenable number.

21433821 is a deficient number, since it is larger than the sum of its proper divisors (8825763).

21433821 is a wasteful number, since it uses less digits than its factorization.

21433821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420291.

The product of its digits is 1152, while the sum is 24.

The square root of 21433821 is about 4629.6674826601. The cubic root of 21433821 is about 277.7792918969.

The spelling of 21433821 in words is "twenty-one million, four hundred thirty-three thousand, eight hundred twenty-one".