42556681 has 2 divisors, whose sum is σ = 42556682. Its totient is φ = 42556680.

The previous prime is 42556649. The next prime is 42556687. The reversal of 42556681 is 18665524.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27657081 + 14899600 = 5259^2 + 3860^2 .

It is a cyclic number.

It is not a de Polignac number, because 42556681 - 2⁵ = 42556649 is a prime.

It is a super-2 number, since 2×42556681² = 3622142195471522, which contains 22 as substring.

It is equal to p_2579419 and since 42556681 and 2579419 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 42556681.

It is not a weakly prime, because it can be changed into another prime (42556687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21278340 + 21278341.

It is an arithmetic number, because the mean of its divisors is an integer number (21278341).

Almost surely, 2^42556681 is an apocalyptic number.

It is an amenable number.

42556681 is a deficient number, since it is larger than the sum of its proper divisors (1).

42556681 is an equidigital number, since it uses as much as digits as its factorization.

42556681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 57600, while the sum is 37.

The square root of 42556681 is about 6523.5481909771. The cubic root of 42556681 is about 349.1316733715.

The spelling of 42556681 in words is "forty-two million, five hundred fifty-six thousand, six hundred eighty-one".