647068021 has 2 divisors, whose sum is σ = 647068022. Its totient is φ = 647068020.

The previous prime is 647067997. The next prime is 647068031. The reversal of 647068021 is 120860746.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 504002500 + 143065521 = 22450^2 + 11961^2 .

It is a cyclic number.

It is not a de Polignac number, because 647068021 - 2⁵ = 647067989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647068031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323534010 + 323534011.

It is an arithmetic number, because the mean of its divisors is an integer number (323534011).

Almost surely, 2^647068021 is an apocalyptic number.

It is an amenable number.

647068021 is a deficient number, since it is larger than the sum of its proper divisors (1).

647068021 is an equidigital number, since it uses as much as digits as its factorization.

647068021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 647068021 is about 25437.5317395379. The cubic root of 647068021 is about 864.9346831632.

It can be divided in two parts, 64706 and 8021, that added together give a palindrome (72727).

The spelling of 647068021 in words is "six hundred forty-seven million, sixty-eight thousand, twenty-one".