6391790221 has 2 divisors, whose sum is σ = 6391790222. Its totient is φ = 6391790220.

The previous prime is 6391790213. The next prime is 6391790261. The reversal of 6391790221 is 1220971936.

It is an a-pointer prime, because the next prime (6391790261) can be obtained adding 6391790221 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6381772996 + 10017225 = 79886^2 + 3165^2 .

It is a cyclic number.

It is not a de Polignac number, because 6391790221 - 2³ = 6391790213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6391790201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3195895110 + 3195895111.

It is an arithmetic number, because the mean of its divisors is an integer number (3195895111).

Almost surely, 2^6391790221 is an apocalyptic number.

It is an amenable number.

6391790221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6391790221 is an equidigital number, since it uses as much as digits as its factorization.

6391790221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 6391790221 is about 79948.6724154942. The cubic root of 6391790221 is about 1855.8413100247.

The spelling of 6391790221 in words is "six billion, three hundred ninety-one million, seven hundred ninety thousand, two hundred twenty-one".