1540639 has 2 divisors, whose sum is σ = 1540640. Its totient is φ = 1540638.

The previous prime is 1540631. The next prime is 1540661. The reversal of 1540639 is 9360451.

It is a weak prime.

It is an emirp because it is prime and its reverse (9360451) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1540639 - 2³ = 1540631 is a prime.

1540639 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1540631) 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, 770319 + 770320.

It is an arithmetic number, because the mean of its divisors is an integer number (770320).

2^1540639 is an apocalyptic number.

1540639 is a deficient number, since it is larger than the sum of its proper divisors (1).

1540639 is an equidigital number, since it uses as much as digits as its factorization.

1540639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 1540639 is about 1241.2247983343. The cubic root of 1540639 is about 115.4960050591.

The spelling of 1540639 in words is "one million, five hundred forty thousand, six hundred thirty-nine".