138921657 has 8 divisors (see below), whose sum is σ = 211690176. Its totient is φ = 79383792.

The previous prime is 138921649. The next prime is 138921659. The reversal of 138921657 is 756129831.

138921657 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 138921657 - 2³ = 138921649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (138921659) 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, 3307638 + ... + 3307679.

It is an arithmetic number, because the mean of its divisors is an integer number (26461272).

Almost surely, 2^138921657 is an apocalyptic number.

It is an amenable number.

138921657 is a deficient number, since it is larger than the sum of its proper divisors (72768519).

138921657 is an equidigital number, since it uses as much as digits as its factorization.

138921657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6615327.

The product of its digits is 90720, while the sum is 42.

The square root of 138921657 is about 11786.5031710003. The cubic root of 138921657 is about 517.9128083791.

The spelling of 138921657 in words is "one hundred thirty-eight million, nine hundred twenty-one thousand, six hundred fifty-seven".