311930021 has 4 divisors (see below), whose sum is σ = 335924652. Its totient is φ = 287935392.

The previous prime is 311929993. The next prime is 311930053. The reversal of 311930021 is 120039113.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120039113 = 9157 ⋅13109.

It can be written as a sum of positive squares in 2 ways, for example, as 63520900 + 248409121 = 7970^2 + 15761^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-311930021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 311929975 and 311930002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (311930621) 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, 11997296 + ... + 11997321.

It is an arithmetic number, because the mean of its divisors is an integer number (83981163).

Almost surely, 2^311930021 is an apocalyptic number.

It is an amenable number.

311930021 is a deficient number, since it is larger than the sum of its proper divisors (23994631).

311930021 is a wasteful number, since it uses less digits than its factorization.

311930021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23994630.

The product of its (nonzero) digits is 162, while the sum is 20.

The square root of 311930021 is about 17661.5407312046. The cubic root of 311930021 is about 678.1915767801.

Adding to 311930021 its reverse (120039113), we get a palindrome (431969134).

The spelling of 311930021 in words is "three hundred eleven million, nine hundred thirty thousand, twenty-one".