138648681 has 48 divisors (see below), whose sum is σ = 221644800. Its totient is φ = 83172096.

The previous prime is 138648667. The next prime is 138648701. The reversal of 138648681 is 186846831.

It is a happy number.

138648681 is a `hidden beast` number, since 13 + 86 + 486 + 81 = 666.

It is not a de Polignac number, because 138648681 - 2⁷ = 138648553 is a prime.

It is a super-2 number, since 2×138648681² = 38446913486079522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (138648581) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 361816 + ... + 362198.

It is an arithmetic number, because the mean of its divisors is an integer number (4617600).

Almost surely, 2^138648681 is an apocalyptic number.

It is an amenable number.

138648681 is a deficient number, since it is larger than the sum of its proper divisors (82996119).

138648681 is a wasteful number, since it uses less digits than its factorization.

138648681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 510 (or 507 counting only the distinct ones).

The product of its digits is 221184, while the sum is 45.

The square root of 138648681 is about 11774.9174519399. The cubic root of 138648681 is about 517.5733593405.

The spelling of 138648681 in words is "one hundred thirty-eight million, six hundred forty-eight thousand, six hundred eighty-one".