12121991405 has 8 divisors (see below), whose sum is σ = 14582667384. Its totient is φ = 9673408000.

The previous prime is 12121991353. The next prime is 12121991419. The reversal of 12121991405 is 50419912121.

It can be written as a sum of positive squares in 4 ways, for example, as 3363652009 + 8758339396 = 57997^2 + 93586^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 12121991405 - 2⁶ = 12121991341 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3020936 + ... + 3024945.

It is an arithmetic number, because the mean of its divisors is an integer number (1822833423).

Almost surely, 2^12121991405 is an apocalyptic number.

It is an amenable number.

12121991405 is a deficient number, since it is larger than the sum of its proper divisors (2460675979).

12121991405 is an equidigital number, since it uses as much as digits as its factorization.

12121991405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6046287.

The product of its (nonzero) digits is 6480, while the sum is 35.

The spelling of 12121991405 in words is "twelve billion, one hundred twenty-one million, nine hundred ninety-one thousand, four hundred five".