21207308 has 6 divisors (see below), whose sum is σ = 37112796. Its totient is φ = 10603652.

The previous prime is 21207301. The next prime is 21207331. The reversal of 21207308 is 80370212.

It is not an unprimeable number, because it can be changed into a prime (21207301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2650910 + ... + 2650917.

It is an arithmetic number, because the mean of its divisors is an integer number (6185466).

Almost surely, 2^21207308 is an apocalyptic number.

It is an amenable number.

21207308 is a deficient number, since it is larger than the sum of its proper divisors (15905488).

21207308 is a wasteful number, since it uses less digits than its factorization.

21207308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5301831 (or 5301829 counting only the distinct ones).

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

The square root of 21207308 is about 4605.1393029962. The cubic root of 21207308 is about 276.7972989980.

The spelling of 21207308 in words is "twenty-one million, two hundred seven thousand, three hundred eight".