639056381 has 16 divisors (see below), whose sum is σ = 668530800. Its totient is φ = 610375680.

The previous prime is 639056347. The next prime is 639056387. The reversal of 639056381 is 183650936.

It can be written as a sum of positive squares in 8 ways, for example, as 50993881 + 588062500 = 7141^2 + 24250^2 .

It is a cyclic number.

It is not a de Polignac number, because 639056381 - 2¹⁰ = 639055357 is a prime.

It is a super-2 number, since 2×639056381² = 816786116193634322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639056387) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 445241 + ... + 446673.

It is an arithmetic number, because the mean of its divisors is an integer number (41783175).

Almost surely, 2^639056381 is an apocalyptic number.

It is an amenable number.

639056381 is a deficient number, since it is larger than the sum of its proper divisors (29474419).

639056381 is a wasteful number, since it uses less digits than its factorization.

639056381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1696.

The product of its (nonzero) digits is 116640, while the sum is 41.

The square root of 639056381 is about 25279.5644938753. The cubic root of 639056381 is about 861.3501332076.

The spelling of 639056381 in words is "six hundred thirty-nine million, fifty-six thousand, three hundred eighty-one".