391129009 has 4 divisors (see below), whose sum is σ = 391199220. Its totient is φ = 391058800.

The previous prime is 391128949. The next prime is 391129043. The reversal of 391129009 is 900921193.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 900921193 = 1669 ⋅539797.

It can be written as a sum of positive squares in 2 ways, for example, as 341214784 + 49914225 = 18472^2 + 7065^2 .

It is a cyclic number.

It is not a de Polignac number, because 391129009 - 2⁹ = 391128497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391129069) 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, 25954 + ... + 38155.

It is an arithmetic number, because the mean of its divisors is an integer number (97799805).

Almost surely, 2^391129009 is an apocalyptic number.

It is an amenable number.

391129009 is a deficient number, since it is larger than the sum of its proper divisors (70211).

391129009 is an equidigital number, since it uses as much as digits as its factorization.

391129009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70210.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 391129009 is about 19776.9817970286. The cubic root of 391129009 is about 731.3186954335.

The spelling of 391129009 in words is "three hundred ninety-one million, one hundred twenty-nine thousand, nine".