21285783 has 12 divisors (see below), whose sum is σ = 31400928. Its totient is φ = 13888320.

The previous prime is 21285769. The next prime is 21285791. The reversal of 21285783 is 38758212.

It is not a de Polignac number, because 21285783 - 2¹⁷ = 21154711 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21285703) 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 11 ways as a sum of consecutive naturals, for example, 24738 + ... + 25583.

It is an arithmetic number, because the mean of its divisors is an integer number (2616744).

Almost surely, 2^21285783 is an apocalyptic number.

21285783 is a deficient number, since it is larger than the sum of its proper divisors (10115145).

21285783 is a wasteful number, since it uses less digits than its factorization.

21285783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50374 (or 50371 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 21285783 is about 4613.6518074081. The cubic root of 21285783 is about 277.1382967051.

The spelling of 21285783 in words is "twenty-one million, two hundred eighty-five thousand, seven hundred eighty-three".