21552538 has 8 divisors (see below), whose sum is σ = 36947232. Its totient is φ = 9236796.

The previous prime is 21552529. The next prime is 21552551. The reversal of 21552538 is 83525512.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 769720 + ... + 769747.

It is an arithmetic number, because the mean of its divisors is an integer number (4618404).

Almost surely, 2^21552538 is an apocalyptic number.

21552538 is a deficient number, since it is larger than the sum of its proper divisors (15394694).

21552538 is a wasteful number, since it uses less digits than its factorization.

21552538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1539476.

The product of its digits is 12000, while the sum is 31.

The square root of 21552538 is about 4642.4711092262. The cubic root of 21552538 is about 278.2911997927.

The spelling of 21552538 in words is "twenty-one million, five hundred fifty-two thousand, five hundred thirty-eight".