21287883 has 4 divisors (see below), whose sum is σ = 28383848. Its totient is φ = 14191920.

The previous prime is 21287879. The next prime is 21287909. The reversal of 21287883 is 38878212.

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

It is not a de Polignac number, because 21287883 - 2² = 21287879 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21287873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3547978 + ... + 3547983.

It is an arithmetic number, because the mean of its divisors is an integer number (7095962).

Almost surely, 2^21287883 is an apocalyptic number.

21287883 is a deficient number, since it is larger than the sum of its proper divisors (7095965).

21287883 is an equidigital number, since it uses as much as digits as its factorization.

21287883 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7095964.

The product of its digits is 43008, while the sum is 39.

The square root of 21287883 is about 4613.8793872402. The cubic root of 21287883 is about 277.1474103200.

It can be divided in two parts, 2128 and 7883, that added together give a triangular number (10011 = T₁₄₁).

The spelling of 21287883 in words is "twenty-one million, two hundred eighty-seven thousand, eight hundred eighty-three".