391011011221 has 4 divisors (see below), whose sum is σ = 391012271244. Its totient is φ = 391009751200.

The previous prime is 391011011219. The next prime is 391011011263. The reversal of 391011011221 is 122110110193.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 333835506225 + 57175504996 = 577785^2 + 239114^2 .

It is a cyclic number.

It is not a de Polignac number, because 391011011221 - 2¹ = 391011011219 is a prime.

It is a super-2 number, since 2×391011011221² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 391011011192 and 391011011201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391011041221) 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, 199761 + ... + 906601.

It is an arithmetic number, because the mean of its divisors is an integer number (97753067811).

Almost surely, 2^391011011221 is an apocalyptic number.

It is an amenable number.

391011011221 is a deficient number, since it is larger than the sum of its proper divisors (1260023).

391011011221 is an equidigital number, since it uses as much as digits as its factorization.

391011011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1260022.

The product of its (nonzero) digits is 108, while the sum is 22.

The spelling of 391011011221 in words is "three hundred ninety-one billion, eleven million, eleven thousand, two hundred twenty-one".