647078521 has 2 divisors, whose sum is σ = 647078522. Its totient is φ = 647078520.

The previous prime is 647078507. The next prime is 647078569. The reversal of 647078521 is 125870746.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 559842921 + 87235600 = 23661^2 + 9340^2 .

It is a cyclic number.

It is not a de Polignac number, because 647078521 - 2²¹ = 644981369 is a prime.

It is a super-2 number, since 2×647078521² = 837421224679094882, which contains 22 as substring.

It is equal to p_33649366 and since 647078521 and 33649366 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (647078321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323539260 + 323539261.

It is an arithmetic number, because the mean of its divisors is an integer number (323539261).

Almost surely, 2^647078521 is an apocalyptic number.

It is an amenable number.

647078521 is a deficient number, since it is larger than the sum of its proper divisors (1).

647078521 is an equidigital number, since it uses as much as digits as its factorization.

647078521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 94080, while the sum is 40.

The square root of 647078521 is about 25437.7381266495. The cubic root of 647078521 is about 864.9393615817.

The spelling of 647078521 in words is "six hundred forty-seven million, seventy-eight thousand, five hundred twenty-one".