647661373 has 2 divisors, whose sum is σ = 647661374. Its totient is φ = 647661372.

The previous prime is 647661319. The next prime is 647661403. The reversal of 647661373 is 373166746.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 356378884 + 291282489 = 18878^2 + 17067^2 .

It is a cyclic number.

It is not a de Polignac number, because 647661373 - 2⁹ = 647660861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647661473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323830686 + 323830687.

It is an arithmetic number, because the mean of its divisors is an integer number (323830687).

Almost surely, 2^647661373 is an apocalyptic number.

It is an amenable number.

647661373 is a deficient number, since it is larger than the sum of its proper divisors (1).

647661373 is an equidigital number, since it uses as much as digits as its factorization.

647661373 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024, while the sum is 43.

The square root of 647661373 is about 25449.1919911026. The cubic root of 647661373 is about 865.1989799184.

The spelling of 647661373 in words is "six hundred forty-seven million, six hundred sixty-one thousand, three hundred seventy-three".