639520625 has 20 divisors (see below), whose sum is σ = 808194420. Its totient is φ = 505824000.

The previous prime is 639520613. The next prime is 639520633. The reversal of 639520625 is 526025936.

639520625 = T₃₂₀ + T₃₂₁ + ... + T₁₅₆₉.

It can be written as a sum of positive squares in 10 ways, for example, as 548871184 + 90649441 = 23428^2 + 9521^2 .

It is not a de Polignac number, because 639520625 - 2¹² = 639516529 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 49877 + ... + 61373.

It is an arithmetic number, because the mean of its divisors is an integer number (40409721).

Almost surely, 2^639520625 is an apocalyptic number.

It is an amenable number.

639520625 is a deficient number, since it is larger than the sum of its proper divisors (168673795).

639520625 is an equidigital number, since it uses as much as digits as its factorization.

639520625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11606 (or 11591 counting only the distinct ones).

The product of its (nonzero) digits is 97200, while the sum is 38.

The square root of 639520625 is about 25288.7450261969. The cubic root of 639520625 is about 861.5586593260.

The spelling of 639520625 in words is "six hundred thirty-nine million, five hundred twenty thousand, six hundred twenty-five".