642781439 has 2 divisors, whose sum is σ = 642781440. Its totient is φ = 642781438.

The previous prime is 642781423. The next prime is 642781487. The reversal of 642781439 is 934187246.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 642781439 - 2⁴ = 642781423 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 642781439.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642781409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321390719 + 321390720.

It is an arithmetic number, because the mean of its divisors is an integer number (321390720).

Almost surely, 2^642781439 is an apocalyptic number.

642781439 is a deficient number, since it is larger than the sum of its proper divisors (1).

642781439 is an equidigital number, since it uses as much as digits as its factorization.

642781439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 44.

The square root of 642781439 is about 25353.1346977055. The cubic root of 642781439 is about 863.0204944587.

The spelling of 642781439 in words is "six hundred forty-two million, seven hundred eighty-one thousand, four hundred thirty-nine".