42403981 has 2 divisors, whose sum is σ = 42403982. Its totient is φ = 42403980.

The previous prime is 42403979. The next prime is 42404017. The reversal of 42403981 is 18930424.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28408900 + 13995081 = 5330^2 + 3741^2 .

It is a cyclic number.

It is not a de Polignac number, because 42403981 - 2¹ = 42403979 is a prime.

It is a super-2 number, since 2×42403981² = 3596195209296722, which contains 22 as substring.

Together with 42403979, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42403901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21201990 + 21201991.

It is an arithmetic number, because the mean of its divisors is an integer number (21201991).

Almost surely, 2^42403981 is an apocalyptic number.

It is an amenable number.

42403981 is a deficient number, since it is larger than the sum of its proper divisors (1).

42403981 is an equidigital number, since it uses as much as digits as its factorization.

42403981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 42403981 is about 6511.8339198723. The cubic root of 42403981 is about 348.7135933185.

The spelling of 42403981 in words is "forty-two million, four hundred three thousand, nine hundred eighty-one".