6981639557 has 8 divisors (see below), whose sum is σ = 7175810712. Its totient is φ = 6787756800.

The previous prime is 6981639523. The next prime is 6981639563. The reversal of 6981639557 is 7559361896.

It can be written as a sum of positive squares in 4 ways, for example, as 2203926916 + 4777712641 = 46946^2 + 69121^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6981639557 - 2⁶ = 6981639493 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6981639496 and 6981639505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6981239557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22544 + ... + 120297.

It is an arithmetic number, because the mean of its divisors is an integer number (896976339).

Almost surely, 2^6981639557 is an apocalyptic number.

It is an amenable number.

6981639557 is a deficient number, since it is larger than the sum of its proper divisors (194171155).

6981639557 is a wasteful number, since it uses less digits than its factorization.

6981639557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144199.

The product of its digits is 12247200, while the sum is 59.

The square root of 6981639557 is about 83556.2059753792. The cubic root of 6981639557 is about 1911.2572296103.

The spelling of 6981639557 in words is "six billion, nine hundred eighty-one million, six hundred thirty-nine thousand, five hundred fifty-seven".