30691991 has 4 divisors (see below), whose sum is σ = 33482184. Its totient is φ = 27901800.

The previous prime is 30691979. The next prime is 30692003. The reversal of 30691991 is 19919603.

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

It is an interprime number because it is at equal distance from previous prime (30691979) and next prime (30692003).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-30691991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30691961) 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, 1395080 + ... + 1395101.

It is an arithmetic number, because the mean of its divisors is an integer number (8370546).

Almost surely, 2^30691991 is an apocalyptic number.

30691991 is a deficient number, since it is larger than the sum of its proper divisors (2790193).

30691991 is a wasteful number, since it uses less digits than its factorization.

30691991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2790192.

The product of its (nonzero) digits is 13122, while the sum is 38.

The square root of 30691991 is about 5540.0352886963. The cubic root of 30691991 is about 313.0941987331.

The spelling of 30691991 in words is "thirty million, six hundred ninety-one thousand, nine hundred ninety-one".