21782013 has 8 divisors (see below), whose sum is σ = 31682976. Its totient is φ = 13201200.

The previous prime is 21781997. The next prime is 21782017. The reversal of 21782013 is 31028712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21782013 - 2⁴ = 21781997 is a prime.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21782017) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 329998 + ... + 330063.

It is an arithmetic number, because the mean of its divisors is an integer number (3960372).

Almost surely, 2^21782013 is an apocalyptic number.

It is an amenable number.

21782013 is a deficient number, since it is larger than the sum of its proper divisors (9900963).

21782013 is a wasteful number, since it uses less digits than its factorization.

21782013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660075.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 21782013 is about 4667.1204184165. The cubic root of 21782013 is about 279.2753925743.

The spelling of 21782013 in words is "twenty-one million, seven hundred eighty-two thousand, thirteen".