6391291221 has 24 divisors (see below), whose sum is σ = 11009431680. Its totient is φ = 3493375776.

The previous prime is 6391291183. The next prime is 6391291271. The reversal of 6391291221 is 1221921936.

6391291221 is a `hidden beast` number, since 63 + 91 + 291 + 221 = 666.

It is not a de Polignac number, because 6391291221 - 2⁶ = 6391291157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6391291271) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2203966 + ... + 2206863.

It is an arithmetic number, because the mean of its divisors is an integer number (458726320).

Almost surely, 2^6391291221 is an apocalyptic number.

It is an amenable number.

6391291221 is a deficient number, since it is larger than the sum of its proper divisors (4618140459).

6391291221 is a wasteful number, since it uses less digits than its factorization.

6391291221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4410865 (or 4410862 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 6391291221 is about 79945.5516023249. The cubic root of 6391291221 is about 1855.7930142744.

The spelling of 6391291221 in words is "six billion, three hundred ninety-one million, two hundred ninety-one thousand, two hundred twenty-one".