647720387 has 4 divisors (see below), whose sum is σ = 658338816. Its totient is φ = 637101960.

The previous prime is 647720377. The next prime is 647720429. The reversal of 647720387 is 783027746.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 783027746 = 2 ⋅391513873.

It is a cyclic number.

It is not a de Polignac number, because 647720387 - 2⁴ = 647720371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (647720347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5309123 + ... + 5309244.

It is an arithmetic number, because the mean of its divisors is an integer number (164584704).

Almost surely, 2^647720387 is an apocalyptic number.

647720387 is a deficient number, since it is larger than the sum of its proper divisors (10618429).

647720387 is a wasteful number, since it uses less digits than its factorization.

647720387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10618428.

The product of its (nonzero) digits is 395136, while the sum is 44.

The square root of 647720387 is about 25450.3514121122. The cubic root of 647720387 is about 865.2252576946.

The spelling of 647720387 in words is "six hundred forty-seven million, seven hundred twenty thousand, three hundred eighty-seven".