30904781 has 2 divisors, whose sum is σ = 30904782. Its totient is φ = 30904780.

The previous prime is 30904771. The next prime is 30904789. The reversal of 30904781 is 18740903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27984100 + 2920681 = 5290^2 + 1709^2 .

It is an emirp because it is prime and its reverse (18740903) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 30904781 - 2¹⁰ = 30903757 is a prime.

It is a super-2 number, since 2×30904781² = 1910210977315922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (30904789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15452390 + 15452391.

It is an arithmetic number, because the mean of its divisors is an integer number (15452391).

Almost surely, 2^30904781 is an apocalyptic number.

It is an amenable number.

30904781 is a deficient number, since it is larger than the sum of its proper divisors (1).

30904781 is an equidigital number, since it uses as much as digits as its factorization.

30904781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 30904781 is about 5559.2068678904. The cubic root of 30904781 is about 313.8161019013.

The spelling of 30904781 in words is "thirty million, nine hundred four thousand, seven hundred eighty-one".