647221565 has 32 divisors (see below), whose sum is σ = 836213760. Its totient is φ = 479808000.

The previous prime is 647221559. The next prime is 647221579. The reversal of 647221565 is 565122746.

It is not a de Polignac number, because 647221565 - 2¹⁸ = 646959421 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 615290 + ... + 616340.

It is an arithmetic number, because the mean of its divisors is an integer number (26131680).

Almost surely, 2^647221565 is an apocalyptic number.

It is an amenable number.

647221565 is a deficient number, since it is larger than the sum of its proper divisors (188992195).

647221565 is a wasteful number, since it uses less digits than its factorization.

647221565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1253.

The product of its digits is 100800, while the sum is 38.

The square root of 647221565 is about 25440.5496206352. The cubic root of 647221565 is about 865.0030917506.

The spelling of 647221565 in words is "six hundred forty-seven million, two hundred twenty-one thousand, five hundred sixty-five".