30997821 has 16 divisors (see below), whose sum is σ = 42408000. Its totient is φ = 20133120.

The previous prime is 30997807. The next prime is 30997829. The reversal of 30997821 is 12879903.

It is not a de Polignac number, because 30997821 - 2⁵ = 30997789 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 30997821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30997829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19930 + ... + 21428.

It is an arithmetic number, because the mean of its divisors is an integer number (2650500).

Almost surely, 2^30997821 is an apocalyptic number.

It is an amenable number.

30997821 is a deficient number, since it is larger than the sum of its proper divisors (11410179).

30997821 is a wasteful number, since it uses less digits than its factorization.

30997821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1676.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 30997821 is about 5567.5686794147. The cubic root of 30997821 is about 314.1307047780.

The spelling of 30997821 in words is "thirty million, nine hundred ninety-seven thousand, eight hundred twenty-one".