9780138857 has 2 divisors, whose sum is σ = 9780138858. Its totient is φ = 9780138856.

The previous prime is 9780138847. The next prime is 9780138871. The reversal of 9780138857 is 7588310879.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9483059161 + 297079696 = 97381^2 + 17236^2 .

It is a cyclic number.

It is not a de Polignac number, because 9780138857 - 2¹² = 9780134761 is a prime.

It is a super-2 number, since 2×9780138857² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (9780138847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4890069428 + 4890069429.

It is an arithmetic number, because the mean of its divisors is an integer number (4890069429).

Almost surely, 2^9780138857 is an apocalyptic number.

It is an amenable number.

9780138857 is a deficient number, since it is larger than the sum of its proper divisors (1).

9780138857 is an equidigital number, since it uses as much as digits as its factorization.

9780138857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3386880, while the sum is 56.

The square root of 9780138857 is about 98894.5845686203. The cubic root of 9780138857 is about 2138.5283252964.

The spelling of 9780138857 in words is "nine billion, seven hundred eighty million, one hundred thirty-eight thousand, eight hundred fifty-seven".