21264287 has 16 divisors (see below), whose sum is σ = 24779520. Its totient is φ = 18043200.

The previous prime is 21264251. The next prime is 21264293. The reversal of 21264287 is 78246212.

It is a cyclic number.

It is not a de Polignac number, because 21264287 - 2⁶ = 21264223 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21264487) 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, 14123 + ... + 15555.

It is an arithmetic number, because the mean of its divisors is an integer number (1548720).

Almost surely, 2^21264287 is an apocalyptic number.

21264287 is a deficient number, since it is larger than the sum of its proper divisors (3515233).

21264287 is a wasteful number, since it uses less digits than its factorization.

21264287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1534.

The product of its digits is 10752, while the sum is 32.

The square root of 21264287 is about 4611.3216109918. The cubic root of 21264287 is about 277.0449735177.

The spelling of 21264287 in words is "twenty-one million, two hundred sixty-four thousand, two hundred eighty-seven".