21783089 has 4 divisors (see below), whose sum is σ = 22534260. Its totient is φ = 21031920.

The previous prime is 21783077. The next prime is 21783119. The reversal of 21783089 is 98038712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 17783089 + 4000000 = 4217^2 + 2000^2 .

It is a cyclic number.

It is not a de Polignac number, because 21783089 - 2¹² = 21778993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21783019) 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, 375542 + ... + 375599.

It is an arithmetic number, because the mean of its divisors is an integer number (5633565).

Almost surely, 2^21783089 is an apocalyptic number.

21783089 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21783089 is a deficient number, since it is larger than the sum of its proper divisors (751171).

21783089 is an equidigital number, since it uses as much as digits as its factorization.

21783089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 751170.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 21783089 is about 4667.2356914988. The cubic root of 21783089 is about 279.2799910990.

The spelling of 21783089 in words is "twenty-one million, seven hundred eighty-three thousand, eighty-nine".