491639 has 2 divisors, whose sum is σ = 491640. Its totient is φ = 491638.

The previous prime is 491633. The next prime is 491651. The reversal of 491639 is 936194.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 491639 - 2¹⁶ = 426103 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (491633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245819 + 245820.

It is an arithmetic number, because the mean of its divisors is an integer number (245820).

2⁴⁹¹⁶³⁹ is an apocalyptic number.

491639 is a deficient number, since it is larger than the sum of its proper divisors (1).

491639 is an equidigital number, since it uses as much as digits as its factorization.

491639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5832, while the sum is 32.

The square root of 491639 is about 701.1697369396. The cubic root of 491639 is about 78.9251547717.

The spelling of 491639 in words is "four hundred ninety-one thousand, six hundred thirty-nine".