21131306 has 32 divisors (see below), whose sum is σ = 40383360. Its totient is φ = 8073216.

The previous prime is 21131293. The next prime is 21131317. The reversal of 21131306 is 60313112.

21131306 = T₁₈₈ + T₁₈₉ + ... + T₅₁₀.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2186 + ... + 6858.

It is an arithmetic number, because the mean of its divisors is an integer number (1261980).

Almost surely, 2^21131306 is an apocalyptic number.

21131306 is a deficient number, since it is larger than the sum of its proper divisors (19252054).

21131306 is a wasteful number, since it uses less digits than its factorization.

21131306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4718.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 21131306 is about 4596.8800288892. The cubic root of 21131306 is about 276.4662444200.

Adding to 21131306 its reverse (60313112), we get a palindrome (81444418).

The spelling of 21131306 in words is "twenty-one million, one hundred thirty-one thousand, three hundred six".