639331 has 24 divisors (see below), whose sum is σ = 877824. Its totient is φ = 451440.

The previous prime is 639329. The next prime is 639337. The reversal of 639331 is 133936.

639331 = T₂₃₀ + T₂₃₁ + ... + T₂₅₁.

It is not a de Polignac number, because 639331 - 2¹ = 639329 is a prime.

It is a super-2 number, since 2×639331² = 817488255122, which contains 22 as substring.

It is a Duffinian number.

639331 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 639296 and 639305.

It is not an unprimeable number, because it can be changed into a prime (639337) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 27786 + ... + 27808.

It is an arithmetic number, because the mean of its divisors is an integer number (36576).

2⁶³⁹³³¹ is an apocalyptic number.

639331 is the 506-th heptagonal number.

639331 is a deficient number, since it is larger than the sum of its proper divisors (238493).

639331 is a wasteful number, since it uses less digits than its factorization.

639331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79 (or 60 counting only the distinct ones).

The product of its digits is 1458, while the sum is 25.

The square root of 639331 is about 799.5817656750. The cubic root of 639331 is about 86.1473496990.

The spelling of 639331 in words is "six hundred thirty-nine thousand, three hundred thirty-one".