30991481 has 2 divisors, whose sum is σ = 30991482. Its totient is φ = 30991480.

The previous prime is 30991447. The next prime is 30991501. The reversal of 30991481 is 18419903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26173456 + 4818025 = 5116^2 + 2195^2 .

It is an emirp because it is prime and its reverse (18419903) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 30991481 - 2¹⁸ = 30729337 is a prime.

It is a super-2 number, since 2×30991481² = 1920943789146722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (30991421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15495740 + 15495741.

It is an arithmetic number, because the mean of its divisors is an integer number (15495741).

Almost surely, 2^30991481 is an apocalyptic number.

It is an amenable number.

30991481 is a deficient number, since it is larger than the sum of its proper divisors (1).

30991481 is an equidigital number, since it uses as much as digits as its factorization.

30991481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 30991481 is about 5566.9992814801. Note that the first 3 decimals coincide. The cubic root of 30991481 is about 314.1092868805.

The spelling of 30991481 in words is "thirty million, nine hundred ninety-one thousand, four hundred eighty-one".