21717952 has 28 divisors (see below), whose sum is σ = 43810936. Its totient is φ = 10679040.

The previous prime is 21717937. The next prime is 21717953. The reversal of 21717952 is 25971712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21717953) 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, 1123 + ... + 6685.

Almost surely, 2^21717952 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 21717952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21905468).

21717952 is an abundant number, since it is smaller than the sum of its proper divisors (22092984).

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

21717952 is an equidigital number, since it uses as much as digits as its factorization.

21717952 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5636 (or 5626 counting only the distinct ones).

The product of its digits is 8820, while the sum is 34.

The square root of 21717952 is about 4660.2523536821. The cubic root of 21717952 is about 279.0013403326.

The spelling of 21717952 in words is "twenty-one million, seven hundred seventeen thousand, nine hundred fifty-two".