312920021 has 2 divisors, whose sum is σ = 312920022. Its totient is φ = 312920020.

The previous prime is 312920017. The next prime is 312920029. The reversal of 312920021 is 120029213.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 273406225 + 39513796 = 16535^2 + 6286^2 .

It is a cyclic number.

It is not a de Polignac number, because 312920021 - 2² = 312920017 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 312919975 and 312920002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (312920029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 156460010 + 156460011.

It is an arithmetic number, because the mean of its divisors is an integer number (156460011).

Almost surely, 2^312920021 is an apocalyptic number.

It is an amenable number.

312920021 is a deficient number, since it is larger than the sum of its proper divisors (1).

312920021 is an equidigital number, since it uses as much as digits as its factorization.

312920021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 312920021 is about 17689.5455283622. The cubic root of 312920021 is about 678.9082980119.

Adding to 312920021 its reverse (120029213), we get a palindrome (432949234).

The spelling of 312920021 in words is "three hundred twelve million, nine hundred twenty thousand, twenty-one".