21717164 has 12 divisors (see below), whose sum is σ = 43434384. Its totient is φ = 9307344.

The previous prime is 21717161. The next prime is 21717169. The reversal of 21717164 is 46171712.

21717164 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21717161) 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, 387779 + ... + 387834.

It is an arithmetic number, because the mean of its divisors is an integer number (3619532).

Almost surely, 2^21717164 is an apocalyptic number.

It is an amenable number.

21717164 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21717164 is a wasteful number, since it uses less digits than its factorization.

21717164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775624 (or 775622 counting only the distinct ones).

The product of its digits is 2352, while the sum is 29.

The square root of 21717164 is about 4660.1678081374. The cubic root of 21717164 is about 278.9979659243.

Adding to 21717164 its reverse (46171712), we get a palindrome (67888876).

The spelling of 21717164 in words is "twenty-one million, seven hundred seventeen thousand, one hundred sixty-four".