647211979 has 2 divisors, whose sum is σ = 647211980. Its totient is φ = 647211978.

The previous prime is 647211923. The next prime is 647211989. The reversal of 647211979 is 979112746.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 647211979 - 2²³ = 638823371 is a prime.

It is a super-2 number, since 2×647211979² = 837766691522192882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (647211989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323605989 + 323605990.

It is an arithmetic number, because the mean of its divisors is an integer number (323605990).

Almost surely, 2^647211979 is an apocalyptic number.

647211979 is a deficient number, since it is larger than the sum of its proper divisors (1).

647211979 is an equidigital number, since it uses as much as digits as its factorization.

647211979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 190512, while the sum is 46.

The square root of 647211979 is about 25440.3612199198. The cubic root of 647211979 is about 864.9988212086.

The spelling of 647211979 in words is "six hundred forty-seven million, two hundred eleven thousand, nine hundred seventy-nine".