30797821 has 4 divisors (see below), whose sum is σ = 30836700. Its totient is φ = 30758944.

The previous prime is 30797807. The next prime is 30797843. The reversal of 30797821 is 12879703.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12879703 = 191 ⋅67433.

It can be written as a sum of positive squares in 2 ways, for example, as 23716900 + 7080921 = 4870^2 + 2661^2 .

It is a cyclic number.

It is not a de Polignac number, because 30797821 - 2¹¹ = 30795773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30797891) 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, 18226 + ... + 19843.

It is an arithmetic number, because the mean of its divisors is an integer number (7709175).

Almost surely, 2^30797821 is an apocalyptic number.

It is an amenable number.

30797821 is a deficient number, since it is larger than the sum of its proper divisors (38879).

30797821 is an equidigital number, since it uses as much as digits as its factorization.

30797821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38878.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 30797821 is about 5549.5784524592. The cubic root of 30797821 is about 313.4536491568.

The spelling of 30797821 in words is "thirty million, seven hundred ninety-seven thousand, eight hundred twenty-one".