21287363 has 4 divisors (see below), whose sum is σ = 22021440. Its totient is φ = 20553288.

The previous prime is 21287347. The next prime is 21287389. The reversal of 21287363 is 36378212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21287363 - 2⁴ = 21287347 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21287303) 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, 366995 + ... + 367052.

It is an arithmetic number, because the mean of its divisors is an integer number (5505360).

Almost surely, 2^21287363 is an apocalyptic number.

21287363 is a deficient number, since it is larger than the sum of its proper divisors (734077).

21287363 is an equidigital number, since it uses as much as digits as its factorization.

21287363 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 734076.

The product of its digits is 12096, while the sum is 32.

The square root of 21287363 is about 4613.8230351846. The cubic root of 21287363 is about 277.1451536712.

The spelling of 21287363 in words is "twenty-one million, two hundred eighty-seven thousand, three hundred sixty-three".