21617712 has 80 divisors (see below), whose sum is σ = 62634880. Its totient is φ = 7138368.

The previous prime is 21617707. The next prime is 21617747. The reversal of 21617712 is 21771612.

It is a super-2 number, since 2×21617712² = 934650944229888, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 70263 + ... + 70569.

It is an arithmetic number, because the mean of its divisors is an integer number (782936).

Almost surely, 2^21617712 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 21617712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31317440).

21617712 is an abundant number, since it is smaller than the sum of its proper divisors (41017168).

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

21617712 is a wasteful number, since it uses less digits than its factorization.

21617712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487 (or 475 counting only the distinct ones).

The product of its digits is 1176, while the sum is 27.

The square root of 21617712 is about 4649.4851327862. The cubic root of 21617712 is about 278.5714312764.

The spelling of 21617712 in words is "twenty-one million, six hundred seventeen thousand, seven hundred twelve".