21640088 has 16 divisors (see below), whose sum is σ = 42711000. Its totient is φ = 10250496.

The previous prime is 21640081. The next prime is 21640121. The reversal of 21640088 is 88004612.

It is a self number, because there is not a number n which added to its sum of digits gives 21640088.

It is a congruent number.

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, 71033 + ... + 71336.

Almost surely, 2^21640088 is an apocalyptic number.

It is an amenable number.

21640088 is a deficient number, since it is larger than the sum of its proper divisors (21070912).

21640088 is a wasteful number, since it uses less digits than its factorization.

21640088 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142394 (or 142390 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 21640088 is about 4651.8907983744. The cubic root of 21640088 is about 278.6675124425.

It can be divided in two parts, 216 and 40088, that added together give a palindrome (40304).

The spelling of 21640088 in words is "twenty-one million, six hundred forty thousand, eighty-eight".