21071320 has 32 divisors (see below), whose sum is σ = 48942720. Its totient is φ = 8156160.

The previous prime is 21071287. The next prime is 21071321. The reversal of 21071320 is 2317012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21071294 and 21071303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21071321) 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, 7257 + ... + 9736.

It is an arithmetic number, because the mean of its divisors is an integer number (1529460).

Almost surely, 2^21071320 is an apocalyptic number.

21071320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21071320 is an abundant number, since it is smaller than the sum of its proper divisors (27871400).

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

21071320 is a wasteful number, since it uses less digits than its factorization.

21071320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17035 (or 17031 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21071320 is about 4590.3507491258. The cubic root of 21071320 is about 276.2043924626.

Adding to 21071320 its reverse (2317012), we get a palindrome (23388332).

The spelling of 21071320 in words is "twenty-one million, seventy-one thousand, three hundred twenty".