21071712 has 48 divisors (see below), whose sum is σ = 55641600. Its totient is φ = 6982272.

The previous prime is 21071707. The next prime is 21071717. The reversal of 21071712 is 21717012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21071707) and next prime (21071717).

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×21071712² = 888034093221888, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21071717) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18553 + ... + 19655.

It is an arithmetic number, because the mean of its divisors is an integer number (1159200).

Almost surely, 2^21071712 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 21071712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27820800).

21071712 is an abundant number, since it is smaller than the sum of its proper divisors (34569888).

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

21071712 is a wasteful number, since it uses less digits than its factorization.

21071712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1315 (or 1307 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 21.

The square root of 21071712 is about 4590.3934471895. The cubic root of 21071712 is about 276.2061052402.

Adding to 21071712 its reverse (21717012), we get a palindrome (42788724).

The spelling of 21071712 in words is "twenty-one million, seventy-one thousand, seven hundred twelve".