21642783 has 16 divisors (see below), whose sum is σ = 29362176. Its totient is φ = 14178560.

The previous prime is 21642773. The next prime is 21642791. The reversal of 21642783 is 38724612.

It is a cyclic number.

It is not a de Polignac number, because 21642783 - 2⁸ = 21642527 is a prime.

It is a Smith number, since the sum of its digits (33) 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 (21642763) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 61135 + ... + 61487.

It is an arithmetic number, because the mean of its divisors is an integer number (1835136).

Almost surely, 2^21642783 is an apocalyptic number.

21642783 is a deficient number, since it is larger than the sum of its proper divisors (7719393).

21642783 is a wasteful number, since it uses less digits than its factorization.

21642783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 654.

The product of its digits is 16128, while the sum is 33.

The square root of 21642783 is about 4652.1804565171. The cubic root of 21642783 is about 278.6790801368.

The spelling of 21642783 in words is "twenty-one million, six hundred forty-two thousand, seven hundred eighty-three".