649639 has 2 divisors, whose sum is σ = 649640. Its totient is φ = 649638.

The previous prime is 649633. The next prime is 649643. The reversal of 649639 is 936946.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 649639 - 2³ = 649631 is a prime.

649639 is a lucky number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 649598 and 649607.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (649631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324819 + 324820.

It is an arithmetic number, because the mean of its divisors is an integer number (324820).

2⁶⁴⁹⁶³⁹ is an apocalyptic number.

649639 is a deficient number, since it is larger than the sum of its proper divisors (1).

649639 is an equidigital number, since it uses as much as digits as its factorization.

649639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 37.

The square root of 649639 is about 806.0018610400. The cubic root of 649639 is about 86.6078710353.

The spelling of 649639 in words is "six hundred forty-nine thousand, six hundred thirty-nine".