30991387 has 4 divisors (see below), whose sum is σ = 35418736. Its totient is φ = 26564040.

The previous prime is 30991381. The next prime is 30991397. The reversal of 30991387 is 78319903.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-30991387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (30991381) 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, 2213664 + ... + 2213677.

It is an arithmetic number, because the mean of its divisors is an integer number (8854684).

Almost surely, 2^30991387 is an apocalyptic number.

30991387 is a deficient number, since it is larger than the sum of its proper divisors (4427349).

30991387 is an equidigital number, since it uses as much as digits as its factorization.

30991387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4427348.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 30991387 is about 5566.9908388644. The cubic root of 30991387 is about 314.1089693061.

The spelling of 30991387 in words is "thirty million, nine hundred ninety-one thousand, three hundred eighty-seven".