42987221 has 2 divisors, whose sum is σ = 42987222. Its totient is φ = 42987220.

The previous prime is 42987211. The next prime is 42987233. The reversal of 42987221 is 12278924.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42432196 + 555025 = 6514^2 + 745^2 .

It is a cyclic number.

It is not a de Polignac number, because 42987221 - 2¹⁸ = 42725077 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42987211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21493610 + 21493611.

It is an arithmetic number, because the mean of its divisors is an integer number (21493611).

Almost surely, 2^42987221 is an apocalyptic number.

It is an amenable number.

42987221 is a deficient number, since it is larger than the sum of its proper divisors (1).

42987221 is an equidigital number, since it uses as much as digits as its factorization.

42987221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 35.

The square root of 42987221 is about 6556.4640622824. The cubic root of 42987221 is about 350.3050972328.

The spelling of 42987221 in words is "forty-two million, nine hundred eighty-seven thousand, two hundred twenty-one".