21328247 has 2 divisors, whose sum is σ = 21328248. Its totient is φ = 21328246.

The previous prime is 21328213. The next prime is 21328273. The reversal of 21328247 is 74282312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21328247 - 2⁸ = 21327991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21328277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10664123 + 10664124.

It is an arithmetic number, because the mean of its divisors is an integer number (10664124).

Almost surely, 2^21328247 is an apocalyptic number.

21328247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21328247 is an equidigital number, since it uses as much as digits as its factorization.

21328247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5376, while the sum is 29.

The square root of 21328247 is about 4618.2515089588. The cubic root of 21328247 is about 277.3224663223.

The spelling of 21328247 in words is "twenty-one million, three hundred twenty-eight thousand, two hundred forty-seven".