30969781 has 2 divisors, whose sum is σ = 30969782. Its totient is φ = 30969780.

The previous prime is 30969751. The next prime is 30969787. The reversal of 30969781 is 18796903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30802500 + 167281 = 5550^2 + 409^2 .

It is an emirp because it is prime and its reverse (18796903) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 30969781 - 2¹¹ = 30967733 is a prime.

It is a super-2 number, since 2×30969781² = 1918254670375922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (30969787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15484890 + 15484891.

It is an arithmetic number, because the mean of its divisors is an integer number (15484891).

Almost surely, 2^30969781 is an apocalyptic number.

It is an amenable number.

30969781 is a deficient number, since it is larger than the sum of its proper divisors (1).

30969781 is an equidigital number, since it uses as much as digits as its factorization.

30969781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 81648, while the sum is 43.

The square root of 30969781 is about 5565.0499548522. The cubic root of 30969781 is about 314.0359574493.

The spelling of 30969781 in words is "thirty million, nine hundred sixty-nine thousand, seven hundred eighty-one".