21638522 has 8 divisors (see below), whose sum is σ = 33070356. Its totient is φ = 10615072.

The previous prime is 21638509. The next prime is 21638531. The reversal of 21638522 is 22583612.

It can be written as a sum of positive squares in 2 ways, for example, as 21242881 + 395641 = 4609^2 + 629^2 .

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, 101963 + ... + 102174.

Almost surely, 2^21638522 is an apocalyptic number.

21638522 is a deficient number, since it is larger than the sum of its proper divisors (11431834).

21638522 is a wasteful number, since it uses less digits than its factorization.

21638522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204192.

The product of its digits is 5760, while the sum is 29.

The square root of 21638522 is about 4651.7224766746. The cubic root of 21638522 is about 278.6607902909.

The spelling of 21638522 in words is "twenty-one million, six hundred thirty-eight thousand, five hundred twenty-two".