3991100121 has 10 divisors (see below), whose sum is σ = 5962013882. Its totient is φ = 2660733360.

The previous prime is 3991100077. The next prime is 3991100123. The reversal of 3991100121 is 1210011993.

It can be written as a sum of positive squares in only one way, i.e., 2521144521 + 1469955600 = 50211^2 + 38340^2 .

It is not a de Polignac number, because 3991100121 - 2¹¹ = 3991098073 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3991100123) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 24636340 + ... + 24636501.

Almost surely, 2^3991100121 is an apocalyptic number.

It is an amenable number.

3991100121 is a deficient number, since it is larger than the sum of its proper divisors (1970913761).

3991100121 is an equidigital number, since it uses as much as digits as its factorization.

3991100121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49272853 (or 49272844 counting only the distinct ones).

The product of its (nonzero) digits is 486, while the sum is 27.

The square root of 3991100121 is about 63175.1543013549. The cubic root of 3991100121 is about 1586.2228712896. Note that the first 3 decimals are identical.

The spelling of 3991100121 in words is "three billion, nine hundred ninety-one million, one hundred thousand, one hundred twenty-one".