21255783 has 4 divisors (see below), whose sum is σ = 28341048. Its totient is φ = 14170520.

The previous prime is 21255761. The next prime is 21255791. The reversal of 21255783 is 38755212.

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 21255783 - 2¹³ = 21247591 is a prime.

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 (21255733) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3542628 + ... + 3542633.

It is an arithmetic number, because the mean of its divisors is an integer number (7085262).

Almost surely, 2^21255783 is an apocalyptic number.

21255783 is a deficient number, since it is larger than the sum of its proper divisors (7085265).

21255783 is an equidigital number, since it uses as much as digits as its factorization.

21255783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7085264.

The product of its digits is 16800, while the sum is 33.

The square root of 21255783 is about 4610.3994403956. The cubic root of 21255783 is about 277.0080367107.

The spelling of 21255783 in words is "twenty-one million, two hundred fifty-five thousand, seven hundred eighty-three".