647646781477 has 8 divisors (see below), whose sum is σ = 650463829400. Its totient is φ = 644835513600.

The previous prime is 647646781447. The next prime is 647646781501. The reversal of 647646781477 is 774187646746.

It can be written as a sum of positive squares in 4 ways, for example, as 275996825316 + 371649956161 = 525354^2 + 609631^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 647646781477 - 2⁷ = 647646781349 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 (647646781427) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1220352 + ... + 1668697.

It is an arithmetic number, because the mean of its divisors is an integer number (81307978675).

Almost surely, 2^647646781477 is an apocalyptic number.

It is an amenable number.

647646781477 is a deficient number, since it is larger than the sum of its proper divisors (2817047923).

647646781477 is a wasteful number, since it uses less digits than its factorization.

647646781477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2890023.

The product of its digits is 265531392, while the sum is 67.

The spelling of 647646781477 in words is "six hundred forty-seven billion, six hundred forty-six million, seven hundred eighty-one thousand, four hundred seventy-seven".