30189721 has 4 divisors (see below), whose sum is σ = 30201444. Its totient is φ = 30178000.

The previous prime is 30189707. The next prime is 30189751. The reversal of 30189721 is 12798103.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12798103 = 59 ⋅216917.

It can be written as a sum of positive squares in 2 ways, for example, as 24255625 + 5934096 = 4925^2 + 2436^2 .

It is a cyclic number.

It is not a de Polignac number, because 30189721 - 2¹¹ = 30187673 is a prime.

It is a super-2 number, since 2×30189721² = 1822838508115682, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (30189751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130 + ... + 7771.

It is an arithmetic number, because the mean of its divisors is an integer number (7550361).

It is a vampire number, since it can be written as 3821 ⋅ 7901 (with its own digits).

Almost surely, 2^30189721 is an apocalyptic number.

It is an amenable number.

30189721 is a deficient number, since it is larger than the sum of its proper divisors (11723).

30189721 is an equidigital number, since it uses as much as digits as its factorization.

30189721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11722.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 30189721 is about 5494.5173582399. The cubic root of 30189721 is about 311.3768827266.

The spelling of 30189721 in words is "thirty million, one hundred eighty-nine thousand, seven hundred twenty-one".