216971647 has 2 divisors, whose sum is σ = 216971648. Its totient is φ = 216971646.

The previous prime is 216971567. The next prime is 216971653. The reversal of 216971647 is 746179612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 216971647 - 2⁷ = 216971519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216971947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108485823 + 108485824.

It is an arithmetic number, because the mean of its divisors is an integer number (108485824).

Almost surely, 2^216971647 is an apocalyptic number.

216971647 is a deficient number, since it is larger than the sum of its proper divisors (1).

216971647 is an equidigital number, since it uses as much as digits as its factorization.

216971647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 43.

The square root of 216971647 is about 14729.9574676915. The cubic root of 216971647 is about 600.8983274898.

The spelling of 216971647 in words is "two hundred sixteen million, nine hundred seventy-one thousand, six hundred forty-seven".