21226287 has 16 divisors (see below), whose sum is σ = 29912960. Its totient is φ = 13351392.

The previous prime is 21226277. The next prime is 21226291. The reversal of 21226287 is 78262212.

It is not a de Polignac number, because 21226287 - 2¹⁰ = 21225263 is a prime.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21226237) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16893 + ... + 18105.

It is an arithmetic number, because the mean of its divisors is an integer number (1869560).

Almost surely, 2^21226287 is an apocalyptic number.

21226287 is a deficient number, since it is larger than the sum of its proper divisors (8686673).

21226287 is a wasteful number, since it uses less digits than its factorization.

21226287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1542.

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

The square root of 21226287 is about 4607.1994747352. The cubic root of 21226287 is about 276.8798455365.

Adding to 21226287 its reverse (78262212), we get a palindrome (99488499).

The spelling of 21226287 in words is "twenty-one million, two hundred twenty-six thousand, two hundred eighty-seven".