20715647 has 2 divisors, whose sum is σ = 20715648. Its totient is φ = 20715646.

The previous prime is 20715641. The next prime is 20715649. The reversal of 20715647 is 74651702.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20715647 is a prime.

Together with 20715649, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20715641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10357823 + 10357824.

It is an arithmetic number, because the mean of its divisors is an integer number (10357824).

Almost surely, 2^20715647 is an apocalyptic number.

20715647 is a deficient number, since it is larger than the sum of its proper divisors (1).

20715647 is an equidigital number, since it uses as much as digits as its factorization.

20715647 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11760, while the sum is 32.

The square root of 20715647 is about 4551.4444959815. Note that the first 4 decimals coincide. The cubic root of 20715647 is about 274.6415031055.

The spelling of 20715647 in words is "twenty million, seven hundred fifteen thousand, six hundred forty-seven".