30215981 has 2 divisors, whose sum is σ = 30215982. Its totient is φ = 30215980.

The previous prime is 30215957. The next prime is 30215993. The reversal of 30215981 is 18951203.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25593481 + 4622500 = 5059^2 + 2150^2 .

It is a cyclic number.

It is not a de Polignac number, because 30215981 - 2¹⁴ = 30199597 is a prime.

It is a super-2 number, since 2×30215981² = 1826011015584722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen 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 (30215921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15107990 + 15107991.

It is an arithmetic number, because the mean of its divisors is an integer number (15107991).

Almost surely, 2^30215981 is an apocalyptic number.

It is an amenable number.

30215981 is a deficient number, since it is larger than the sum of its proper divisors (1).

30215981 is an equidigital number, since it uses as much as digits as its factorization.

30215981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 30215981 is about 5496.9064936562. The cubic root of 30215981 is about 311.4671384716.

The spelling of 30215981 in words is "thirty million, two hundred fifteen thousand, nine hundred eighty-one".