21156306 has 16 divisors (see below), whose sum is σ = 42536448. Its totient is φ = 7014800.

The previous prime is 21156277. The next prime is 21156307. The reversal of 21156306 is 60365112.

It is not an unprimeable number, because it can be changed into a prime (21156307) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 8085 + ... + 10376.

It is an arithmetic number, because the mean of its divisors is an integer number (2658528).

Almost surely, 2^21156306 is an apocalyptic number.

21156306 is an abundant number, since it is smaller than the sum of its proper divisors (21380142).

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

21156306 is a wasteful number, since it uses less digits than its factorization.

21156306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18657.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21156306 is about 4599.5984607355. The cubic root of 21156306 is about 276.5752285693.

The spelling of 21156306 in words is "twenty-one million, one hundred fifty-six thousand, three hundred six".