647402909 has 4 divisors (see below), whose sum is σ = 656271516. Its totient is φ = 638534304.

The previous prime is 647402893. The next prime is 647402933. The reversal of 647402909 is 909204746.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 909204746 = 2 ⋅454602373.

It can be written as a sum of positive squares in 2 ways, for example, as 566582809 + 80820100 = 23803^2 + 8990^2 .

It is a cyclic number.

It is not a de Polignac number, because 647402909 - 2⁴ = 647402893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647402939) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4434194 + ... + 4434339.

It is an arithmetic number, because the mean of its divisors is an integer number (164067879).

Almost surely, 2^647402909 is an apocalyptic number.

It is an amenable number.

647402909 is a deficient number, since it is larger than the sum of its proper divisors (8868607).

647402909 is an equidigital number, since it uses as much as digits as its factorization.

647402909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8868606.

The product of its (nonzero) digits is 108864, while the sum is 41.

The square root of 647402909 is about 25444.1134449601. The cubic root of 647402909 is about 865.0838721618.

The spelling of 647402909 in words is "six hundred forty-seven million, four hundred two thousand, nine hundred nine".