21783072 has 24 divisors (see below), whose sum is σ = 57180816. Its totient is φ = 7260992.

The previous prime is 21783071. The next prime is 21783077. The reversal of 21783072 is 27038712.

It is a tau number, because it is divible by the number of its divisors (24).

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (21783071) 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, 113358 + ... + 113549.

It is an arithmetic number, because the mean of its divisors is an integer number (2382534).

Almost surely, 2^21783072 is an apocalyptic number.

It is an amenable number.

21783072 is an abundant number, since it is smaller than the sum of its proper divisors (35397744).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21783072 is a wasteful number, since it uses less digits than its factorization.

21783072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226920 (or 226912 counting only the distinct ones).

The product of its (nonzero) digits is 4704, while the sum is 30.

The square root of 21783072 is about 4667.2338702919. The cubic root of 21783072 is about 279.2799184470.

The spelling of 21783072 in words is "twenty-one million, seven hundred eighty-three thousand, seventy-two".