21221733 has 16 divisors (see below), whose sum is σ = 30602880. Its totient is φ = 13003584.

The previous prime is 21221731. The next prime is 21221741. The reversal of 21221733 is 33712212.

It is not a de Polignac number, because 21221733 - 2¹ = 21221731 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221731) 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, 9223 + ... + 11291.

It is an arithmetic number, because the mean of its divisors is an integer number (1912680).

Almost surely, 2^21221733 is an apocalyptic number.

It is an amenable number.

21221733 is a deficient number, since it is larger than the sum of its proper divisors (9381147).

21221733 is a wasteful number, since it uses less digits than its factorization.

21221733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2348.

The product of its digits is 504, while the sum is 21.

The square root of 21221733 is about 4606.7052217393. The cubic root of 21221733 is about 276.8600430309.

Adding to 21221733 its reverse (33712212), we get a palindrome (54933945).

It can be divided in two parts, 212 and 21733, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21221733 in words is "twenty-one million, two hundred twenty-one thousand, seven hundred thirty-three".