21783673 has 4 divisors (see below), whose sum is σ = 21826980. Its totient is φ = 21740368.

The previous prime is 21783667. The next prime is 21783679. The reversal of 21783673 is 37638712.

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

It is an interprime number because it is at equal distance from previous prime (21783667) and next prime (21783679).

It can be written as a sum of positive squares in 2 ways, for example, as 19686969 + 2096704 = 4437^2 + 1448^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21783673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21783679) 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, 20890 + ... + 21907.

It is an arithmetic number, because the mean of its divisors is an integer number (5456745).

Almost surely, 2^21783673 is an apocalyptic number.

It is an amenable number.

21783673 is a deficient number, since it is larger than the sum of its proper divisors (43307).

21783673 is an equidigital number, since it uses as much as digits as its factorization.

21783673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43306.

The product of its digits is 42336, while the sum is 37.

The square root of 21783673 is about 4667.2982548794. The cubic root of 21783673 is about 279.2824868892.

The spelling of 21783673 in words is "twenty-one million, seven hundred eighty-three thousand, six hundred seventy-three".