42689681 has 2 divisors, whose sum is σ = 42689682. Its totient is φ = 42689680.

The previous prime is 42689657. The next prime is 42689687. The reversal of 42689681 is 18698624.

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., 40704400 + 1985281 = 6380^2 + 1409^2 .

It is a cyclic number.

It is not a de Polignac number, because 42689681 - 2⁶ = 42689617 is a prime.

It is a super-3 number, since 3×42689681³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (42689687) 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, 21344840 + 21344841.

It is an arithmetic number, because the mean of its divisors is an integer number (21344841).

Almost surely, 2^42689681 is an apocalyptic number.

It is an amenable number.

42689681 is a deficient number, since it is larger than the sum of its proper divisors (1).

42689681 is an equidigital number, since it uses as much as digits as its factorization.

42689681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165888, while the sum is 44.

The square root of 42689681 is about 6533.7340778455. The cubic root of 42689681 is about 349.4950023265.

The spelling of 42689681 in words is "forty-two million, six hundred eighty-nine thousand, six hundred eighty-one".