21640116 has 96 divisors (see below), whose sum is σ = 56996352. Its totient is φ = 6359040.

The previous prime is 21640081. The next prime is 21640121. The reversal of 21640116 is 61104612.

It is a junction number, because it is equal to n+sod(n) for n = 21640092 and 21640101.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 354726 + ... + 354786.

It is an arithmetic number, because the mean of its divisors is an integer number (593712).

Almost surely, 2^21640116 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21640116, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28498176).

21640116 is an abundant number, since it is smaller than the sum of its proper divisors (35356236).

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

21640116 is a wasteful number, since it uses less digits than its factorization.

21640116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21640116 is about 4651.8938079023. The cubic root of 21640116 is about 278.6676326312.

Adding to 21640116 its reverse (61104612), we get a palindrome (82744728).

The spelling of 21640116 in words is "twenty-one million, six hundred forty thousand, one hundred sixteen".