40642781 has 2 divisors, whose sum is σ = 40642782. Its totient is φ = 40642780.

The previous prime is 40642769. The next prime is 40642787. The reversal of 40642781 is 18724604.

40642781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26429881 + 14212900 = 5141^2 + 3770^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40642781 is a prime.

It is a super-2 number, since 2×40642781² = 3303671294827922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40642787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20321390 + 20321391.

It is an arithmetic number, because the mean of its divisors is an integer number (20321391).

Almost surely, 2^40642781 is an apocalyptic number.

It is an amenable number.

40642781 is a deficient number, since it is larger than the sum of its proper divisors (1).

40642781 is an equidigital number, since it uses as much as digits as its factorization.

40642781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 40642781 is about 6375.1690957966. The cubic root of 40642781 is about 343.8173635034.

The spelling of 40642781 in words is "forty million, six hundred forty-two thousand, seven hundred eighty-one".