30920021 has 4 divisors (see below), whose sum is σ = 33730944. Its totient is φ = 28109100.

The previous prime is 30920017. The next prime is 30920069. The reversal of 30920021 is 12002903.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12002903 = 11 ⋅1091173.

It is a cyclic number.

It is not a de Polignac number, because 30920021 - 2² = 30920017 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 (30920081) 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, 1405445 + ... + 1405466.

It is an arithmetic number, because the mean of its divisors is an integer number (8432736).

Almost surely, 2^30920021 is an apocalyptic number.

It is an amenable number.

30920021 is a deficient number, since it is larger than the sum of its proper divisors (2810923).

30920021 is a wasteful number, since it uses less digits than its factorization.

30920021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2810922.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 30920021 is about 5560.5773980766. The cubic root of 30920021 is about 313.8676772166.

Adding to 30920021 its reverse (12002903), we get a palindrome (42922924).

The spelling of 30920021 in words is "thirty million, nine hundred twenty thousand, twenty-one".