647721220351 has 4 divisors (see below), whose sum is σ = 647728700112. Its totient is φ = 647713740592.

The previous prime is 647721220337. The next prime is 647721220361. The reversal of 647721220351 is 153022127746.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 647721220351 - 2⁹ = 647721219839 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 (647721220361) 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, 3608446 + ... + 3783691.

It is an arithmetic number, because the mean of its divisors is an integer number (161932175028).

Almost surely, 2^647721220351 is an apocalyptic number.

647721220351 is a deficient number, since it is larger than the sum of its proper divisors (7479761).

647721220351 is an equidigital number, since it uses as much as digits as its factorization.

647721220351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7479760.

The product of its (nonzero) digits is 141120, while the sum is 40.

The spelling of 647721220351 in words is "six hundred forty-seven billion, seven hundred twenty-one million, two hundred twenty thousand, three hundred fifty-one".