30991939 has 4 divisors (see below), whose sum is σ = 33809400. Its totient is φ = 28174480.

The previous prime is 30991927. The next prime is 30991943. The reversal of 30991939 is 93919903.

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

It is a cyclic number.

It is not a de Polignac number, because 30991939 - 2⁷ = 30991811 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 30991895 and 30991904.

It is not an unprimeable number, because it can be changed into a prime (30991139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1408714 + ... + 1408735.

It is an arithmetic number, because the mean of its divisors is an integer number (8452350).

Almost surely, 2^30991939 is an apocalyptic number.

30991939 is a deficient number, since it is larger than the sum of its proper divisors (2817461).

30991939 is a wasteful number, since it uses less digits than its factorization.

30991939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2817460.

The product of its (nonzero) digits is 59049, while the sum is 43.

The square root of 30991939 is about 5567.0404165948. The cubic root of 30991939 is about 314.1108342019.

The spelling of 30991939 in words is "thirty million, nine hundred ninety-one thousand, nine hundred thirty-nine".