21365783 has 4 divisors (see below), whose sum is σ = 21484008. Its totient is φ = 21247560.

The previous prime is 21365767. The next prime is 21365791. The reversal of 21365783 is 38756312.

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 21365783 - 2⁴ = 21365767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21365723) 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, 58841 + ... + 59202.

It is an arithmetic number, because the mean of its divisors is an integer number (5371002).

Almost surely, 2^21365783 is an apocalyptic number.

21365783 is a deficient number, since it is larger than the sum of its proper divisors (118225).

21365783 is a wasteful number, since it uses less digits than its factorization.

21365783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118224.

The product of its digits is 30240, while the sum is 35.

The square root of 21365783 is about 4622.3135981887. The cubic root of 21365783 is about 277.4850593909.

The spelling of 21365783 in words is "twenty-one million, three hundred sixty-five thousand, seven hundred eighty-three".