21638026 has 8 divisors (see below), whose sum is σ = 32755140. Its totient is φ = 10719648.

The previous prime is 21637997. The next prime is 21638033. The reversal of 21638026 is 62083612.

It can be written as a sum of positive squares in 2 ways, for example, as 21576025 + 62001 = 4645^2 + 249^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21637985 and 21638003.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49411 + ... + 49846.

Almost surely, 2^21638026 is an apocalyptic number.

21638026 is a deficient number, since it is larger than the sum of its proper divisors (11117114).

21638026 is a wasteful number, since it uses less digits than its factorization.

21638026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99368.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 21638026 is about 4651.6691627845. The cubic root of 21638026 is about 278.6586611127.

The spelling of 21638026 in words is "twenty-one million, six hundred thirty-eight thousand, twenty-six".