21287226 has 8 divisors (see below), whose sum is σ = 42574464. Its totient is φ = 7095740.

The previous prime is 21287221. The next prime is 21287243. The reversal of 21287226 is 62278212.

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

21287226 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21287193 and 21287202.

It is not an unprimeable number, because it can be changed into a prime (21287221) by changing a digit.

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, 1773930 + ... + 1773941.

It is an arithmetic number, because the mean of its divisors is an integer number (5321808).

Almost surely, 2^21287226 is an apocalyptic number.

21287226 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21287226 is a wasteful number, since it uses less digits than its factorization.

21287226 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3547876.

The product of its digits is 5376, while the sum is 30.

The square root of 21287226 is about 4613.8081884708. The cubic root of 21287226 is about 277.1445591249.

The spelling of 21287226 in words is "twenty-one million, two hundred eighty-seven thousand, two hundred twenty-six".