21640082 has 8 divisors (see below), whose sum is σ = 34369596. Its totient is φ = 10183552.

The previous prime is 21640081. The next prime is 21640121. The reversal of 21640082 is 28004612.

It can be written as a sum of positive squares in 2 ways, for example, as 21631801 + 8281 = 4651^2 + 91^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21640081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 318203 + ... + 318270.

Almost surely, 2^21640082 is an apocalyptic number.

21640082 is a deficient number, since it is larger than the sum of its proper divisors (12729514).

21640082 is a wasteful number, since it uses less digits than its factorization.

21640082 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 636492.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21640082 is about 4651.8901534753. The cubic root of 21640082 is about 278.6674866877.

Adding to 21640082 its reverse (28004612), we get a palindrome (49644694).

The spelling of 21640082 in words is "twenty-one million, six hundred forty thousand, eighty-two".