639297381 has 4 divisors (see below), whose sum is σ = 852396512. Its totient is φ = 426198252.

The previous prime is 639297371. The next prime is 639297403. The reversal of 639297381 is 183792936.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 639297381 - 2⁹ = 639296869 is a prime.

It is a super-2 number, since 2×639297381² = 817402282706918322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 639297381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639297331) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106549561 + ... + 106549566.

It is an arithmetic number, because the mean of its divisors is an integer number (213099128).

Almost surely, 2^639297381 is an apocalyptic number.

It is an amenable number.

639297381 is a deficient number, since it is larger than the sum of its proper divisors (213099131).

639297381 is a wasteful number, since it uses less digits than its factorization.

639297381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213099130.

The product of its digits is 489888, while the sum is 48.

The square root of 639297381 is about 25284.3307405990. The cubic root of 639297381 is about 861.4583966300.

The spelling of 639297381 in words is "six hundred thirty-nine million, two hundred ninety-seven thousand, three hundred eighty-one".