21385783 has 2 divisors, whose sum is σ = 21385784. Its totient is φ = 21385782.

The previous prime is 21385781. The next prime is 21385801. The reversal of 21385783 is 38758312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21385783 - 2¹ = 21385781 is a prime.

Together with 21385781, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21385781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10692891 + 10692892.

It is an arithmetic number, because the mean of its divisors is an integer number (10692892).

Almost surely, 2^21385783 is an apocalyptic number.

21385783 is a deficient number, since it is larger than the sum of its proper divisors (1).

21385783 is an equidigital number, since it uses as much as digits as its factorization.

21385783 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 37.

The square root of 21385783 is about 4624.4765109145. The cubic root of 21385783 is about 277.5716147716.

It can be divided in two parts, 2138 and 5783, that added together give a square (7921 = 89²).

The spelling of 21385783 in words is "twenty-one million, three hundred eighty-five thousand, seven hundred eighty-three".