42012821 has 2 divisors, whose sum is σ = 42012822. Its totient is φ = 42012820.

The previous prime is 42012787. The next prime is 42012847. The reversal of 42012821 is 12821024.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39866596 + 2146225 = 6314^2 + 1465^2 .

It is a cyclic number.

It is not a de Polignac number, because 42012821 - 2⁶ = 42012757 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 42012793 and 42012802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42012221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21006410 + 21006411.

It is an arithmetic number, because the mean of its divisors is an integer number (21006411).

Almost surely, 2^42012821 is an apocalyptic number.

It is an amenable number.

42012821 is a deficient number, since it is larger than the sum of its proper divisors (1).

42012821 is an equidigital number, since it uses as much as digits as its factorization.

42012821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 42012821 is about 6481.7297845560. The cubic root of 42012821 is about 347.6380308407.

Adding to 42012821 its reverse (12821024), we get a palindrome (54833845).

The spelling of 42012821 in words is "forty-two million, twelve thousand, eight hundred twenty-one".