40781639 has 2 divisors, whose sum is σ = 40781640. Its totient is φ = 40781638.

The previous prime is 40781633. The next prime is 40781641. The reversal of 40781639 is 93618704.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 40781639 - 2²⁴ = 24004423 is a prime.

Together with 40781641, 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 (40781633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20390819 + 20390820.

It is an arithmetic number, because the mean of its divisors is an integer number (20390820).

Almost surely, 2^40781639 is an apocalyptic number.

40781639 is a deficient number, since it is larger than the sum of its proper divisors (1).

40781639 is an equidigital number, since it uses as much as digits as its factorization.

40781639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 40781639 is about 6386.0503443052. The cubic root of 40781639 is about 344.2084745654.

The spelling of 40781639 in words is "forty million, seven hundred eighty-one thousand, six hundred thirty-nine".