139217681 has 2 divisors, whose sum is σ = 139217682. Its totient is φ = 139217680.

The previous prime is 139217669. The next prime is 139217699. The reversal of 139217681 is 186712931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 104878081 + 34339600 = 10241^2 + 5860^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-139217681 is a prime.

It is a super-2 number, since 2×139217681² = 38763125406035522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (139217651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69608840 + 69608841.

It is an arithmetic number, because the mean of its divisors is an integer number (69608841).

Almost surely, 2^139217681 is an apocalyptic number.

It is an amenable number.

139217681 is a deficient number, since it is larger than the sum of its proper divisors (1).

139217681 is an equidigital number, since it uses as much as digits as its factorization.

139217681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 38.

The square root of 139217681 is about 11799.0542417602. The cubic root of 139217681 is about 518.2804156944.

The spelling of 139217681 in words is "one hundred thirty-nine million, two hundred seventeen thousand, six hundred eighty-one".