21308072 has 16 divisors (see below), whose sum is σ = 42303060. Its totient is φ = 10027264.

The previous prime is 21308059. The next prime is 21308081. The reversal of 21308072 is 27080312.

It can be written as a sum of positive squares in 2 ways, for example, as 21031396 + 276676 = 4586^2 + 526^2 .

It is a super-3 number, since 3×21308072³ (a number of 23 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 78203 + ... + 78474.

Almost surely, 2^21308072 is an apocalyptic number.

It is an amenable number.

21308072 is a deficient number, since it is larger than the sum of its proper divisors (20994988).

21308072 is a wasteful number, since it uses less digits than its factorization.

21308072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156700 (or 156696 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21308072 is about 4616.0667239545. The cubic root of 21308072 is about 277.2349963138.

Adding to 21308072 its reverse (27080312), we get a palindrome (48388384).

The spelling of 21308072 in words is "twenty-one million, three hundred eight thousand, seventy-two".