42618781 has 2 divisors, whose sum is σ = 42618782. Its totient is φ = 42618780.

The previous prime is 42618743. The next prime is 42618799. The reversal of 42618781 is 18781624.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28676025 + 13942756 = 5355^2 + 3734^2 .

It is a cyclic number.

It is not a de Polignac number, because 42618781 - 2²³ = 34230173 is a prime.

It is a super-2 number, since 2×42618781² = 3632720987851922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 42618781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42618181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21309390 + 21309391.

It is an arithmetic number, because the mean of its divisors is an integer number (21309391).

Almost surely, 2^42618781 is an apocalyptic number.

It is an amenable number.

42618781 is a deficient number, since it is larger than the sum of its proper divisors (1).

42618781 is an equidigital number, since it uses as much as digits as its factorization.

42618781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21504, while the sum is 37.

The square root of 42618781 is about 6528.3061355914. The cubic root of 42618781 is about 349.3014120122.

The spelling of 42618781 in words is "forty-two million, six hundred eighteen thousand, seven hundred eighty-one".