647983021 has 4 divisors (see below), whose sum is σ = 740552032. Its totient is φ = 555414012.

The previous prime is 647983013. The next prime is 647983051. The reversal of 647983021 is 120389746.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 647983021 - 2³ = 647983013 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 (647983051) 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, 46284495 + ... + 46284508.

It is an arithmetic number, because the mean of its divisors is an integer number (185138008).

Almost surely, 2^647983021 is an apocalyptic number.

It is an amenable number.

647983021 is a deficient number, since it is larger than the sum of its proper divisors (92569011).

647983021 is an equidigital number, since it uses as much as digits as its factorization.

647983021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92569010.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 647983021 is about 25455.5106214745. The cubic root of 647983021 is about 865.3421841075.

The spelling of 647983021 in words is "six hundred forty-seven million, nine hundred eighty-three thousand, twenty-one".