21506332 has 6 divisors (see below), whose sum is σ = 37636088. Its totient is φ = 10753164.

The previous prime is 21506323. The next prime is 21506333. The reversal of 21506332 is 23360512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506333) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2688288 + ... + 2688295.

Almost surely, 2^21506332 is an apocalyptic number.

It is an amenable number.

21506332 is a deficient number, since it is larger than the sum of its proper divisors (16129756).

21506332 is a wasteful number, since it uses less digits than its factorization.

21506332 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5376587 (or 5376585 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 21506332 is about 4637.4919946023. The cubic root of 21506332 is about 278.0921834276.

Adding to 21506332 its reverse (23360512), we get a palindrome (44866844).

The spelling of 21506332 in words is "twenty-one million, five hundred six thousand, three hundred thirty-two".