42219781 has 2 divisors, whose sum is σ = 42219782. Its totient is φ = 42219780.

The previous prime is 42219773. The next prime is 42219797. The reversal of 42219781 is 18791224.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28037025 + 14182756 = 5295^2 + 3766^2 .

It is a cyclic number.

It is not a de Polignac number, because 42219781 - 2³ = 42219773 is a prime.

It is a super-2 number, since 2×42219781² = 3565019815375922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42219761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21109890 + 21109891.

It is an arithmetic number, because the mean of its divisors is an integer number (21109891).

Almost surely, 2^42219781 is an apocalyptic number.

It is an amenable number.

42219781 is a deficient number, since it is larger than the sum of its proper divisors (1).

42219781 is an equidigital number, since it uses as much as digits as its factorization.

42219781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 34.

The square root of 42219781 is about 6497.6750457375. The cubic root of 42219781 is about 348.2079310712.

The spelling of 42219781 in words is "forty-two million, two hundred nineteen thousand, seven hundred eighty-one".