21304747 has 2 divisors, whose sum is σ = 21304748. Its totient is φ = 21304746.

The previous prime is 21304721. The next prime is 21304753. The reversal of 21304747 is 74740312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21304747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21304147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652373 + 10652374.

It is an arithmetic number, because the mean of its divisors is an integer number (10652374).

Almost surely, 2^21304747 is an apocalyptic number.

21304747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21304747 is an equidigital number, since it uses as much as digits as its factorization.

21304747 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4704, while the sum is 28.

The square root of 21304747 is about 4615.7065547974. The cubic root of 21304747 is about 277.2205752638.

The spelling of 21304747 in words is "twenty-one million, three hundred four thousand, seven hundred forty-seven".