30187921 has 4 divisors (see below), whose sum is σ = 30200500. Its totient is φ = 30175344.

The previous prime is 30187919. The next prime is 30187939. The reversal of 30187921 is 12978103.

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: 12978103 = 103 ⋅126001.

It can be written as a sum of positive squares in 2 ways, for example, as 18181696 + 12006225 = 4264^2 + 3465^2 .

It is a cyclic number.

It is not a de Polignac number, because 30187921 - 2¹ = 30187919 is a prime.

It is a super-2 number, since 2×30187921² = 1822621148604482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (30187021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1446 + ... + 7903.

It is an arithmetic number, because the mean of its divisors is an integer number (7550125).

Almost surely, 2^30187921 is an apocalyptic number.

It is an amenable number.

30187921 is a deficient number, since it is larger than the sum of its proper divisors (12579).

30187921 is an equidigital number, since it uses as much as digits as its factorization.

30187921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12578.

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

The square root of 30187921 is about 5494.3535561520. The cubic root of 30187921 is about 311.3706942016.

The spelling of 30187921 in words is "thirty million, one hundred eighty-seven thousand, nine hundred twenty-one".