30919921 has 4 divisors (see below), whose sum is σ = 31203700. Its totient is φ = 30636144.

The previous prime is 30919891. The next prime is 30919939. The reversal of 30919921 is 12991903.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14630625 + 16289296 = 3825^2 + 4036^2 .

It is a cyclic number.

It is not a de Polignac number, because 30919921 - 2¹⁹ = 30395633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (30919321) 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, 141726 + ... + 141943.

It is an arithmetic number, because the mean of its divisors is an integer number (7800925).

Almost surely, 2^30919921 is an apocalyptic number.

It is an amenable number.

30919921 is a deficient number, since it is larger than the sum of its proper divisors (283779).

30919921 is a wasteful number, since it uses less digits than its factorization.

30919921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283778.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 30919921 is about 5560.5684061973. The cubic root of 30919921 is about 313.8673388511.

The spelling of 30919921 in words is "thirty million, nine hundred nineteen thousand, nine hundred twenty-one".