30139981 has 2 divisors, whose sum is σ = 30139982. Its totient is φ = 30139980.

The previous prime is 30139957. The next prime is 30139999. The reversal of 30139981 is 18993103.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30085225 + 54756 = 5485^2 + 234^2 .

It is a cyclic number.

It is not a de Polignac number, because 30139981 - 2⁷ = 30139853 is a prime.

It is a super-2 number, since 2×30139981² = 1816836909360722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (30130981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15069990 + 15069991.

It is an arithmetic number, because the mean of its divisors is an integer number (15069991).

Almost surely, 2^30139981 is an apocalyptic number.

It is an amenable number.

30139981 is a deficient number, since it is larger than the sum of its proper divisors (1).

30139981 is an equidigital number, since it uses as much as digits as its factorization.

30139981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 30139981 is about 5489.9891621022. The cubic root of 30139981 is about 311.2057825499.

The spelling of 30139981 in words is "thirty million, one hundred thirty-nine thousand, nine hundred eighty-one".