21733821 has 12 divisors (see below), whose sum is σ = 32406400. Its totient is φ = 14021640.

The previous prime is 21733807. The next prime is 21733823. The reversal of 21733821 is 12833712.

It is not a de Polignac number, because 21733821 - 2⁶ = 21733757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21733823) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38671 + ... + 39228.

Almost surely, 2^21733821 is an apocalyptic number.

It is an amenable number.

21733821 is a deficient number, since it is larger than the sum of its proper divisors (10672579).

21733821 is a wasteful number, since it uses less digits than its factorization.

21733821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77936 (or 77933 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 21733821 is about 4661.9546329839. The cubic root of 21733821 is about 279.0692778979.

The spelling of 21733821 in words is "twenty-one million, seven hundred thirty-three thousand, eight hundred twenty-one".