646220321 has 16 divisors (see below), whose sum is σ = 666042048. Its totient is φ = 626808000.

The previous prime is 646220317. The next prime is 646220329. The reversal of 646220321 is 123022646.

It is a cyclic number.

It is not a de Polignac number, because 646220321 - 2² = 646220317 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646220329) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1315886 + ... + 1316376.

It is an arithmetic number, because the mean of its divisors is an integer number (41627628).

Almost surely, 2^646220321 is an apocalyptic number.

It is an amenable number.

646220321 is a deficient number, since it is larger than the sum of its proper divisors (19821727).

646220321 is a wasteful number, since it uses less digits than its factorization.

646220321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832.

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 646220321 is about 25420.8638916934. The cubic root of 646220321 is about 864.5568117380.

Adding to 646220321 its reverse (123022646), we get a palindrome (769242967).

The spelling of 646220321 in words is "six hundred forty-six million, two hundred twenty thousand, three hundred twenty-one".