871639 has 2 divisors, whose sum is σ = 871640. Its totient is φ = 871638.

The previous prime is 871621. The next prime is 871643. The reversal of 871639 is 936178.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-871639 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (871649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 435819 + 435820.

It is an arithmetic number, because the mean of its divisors is an integer number (435820).

2⁸⁷¹⁶³⁹ is an apocalyptic number.

871639 is a deficient number, since it is larger than the sum of its proper divisors (1).

871639 is an equidigital number, since it uses as much as digits as its factorization.

871639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 34.

The square root of 871639 is about 933.6160881219. The cubic root of 871639 is about 95.5239379701.

The spelling of 871639 in words is "eight hundred seventy-one thousand, six hundred thirty-nine".