3991254121 has 4 divisors (see below), whose sum is σ = 4099125892. Its totient is φ = 3883382352.

The previous prime is 3991254097. The next prime is 3991254131. The reversal of 3991254121 is 1214521993.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2621440000 + 1369814121 = 51200^2 + 37011^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3991254121 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 107871733 = 3991254121 / (3 + 9 + 9 + 1 + 2 + 5 + 4 + 1 + 2 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3991254131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53935830 + ... + 53935903.

It is an arithmetic number, because the mean of its divisors is an integer number (1024781473).

Almost surely, 2^3991254121 is an apocalyptic number.

It is an amenable number.

3991254121 is a deficient number, since it is larger than the sum of its proper divisors (107871771).

3991254121 is a wasteful number, since it uses less digits than its factorization.

3991254121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107871770.

The product of its digits is 19440, while the sum is 37.

The square root of 3991254121 is about 63176.3731231859. The cubic root of 3991254121 is about 1586.2432729477.

The spelling of 3991254121 in words is "three billion, nine hundred ninety-one million, two hundred fifty-four thousand, one hundred twenty-one".