139521457 has 4 divisors (see below), whose sum is σ = 141808756. Its totient is φ = 137234160.

The previous prime is 139521449. The next prime is 139521491. The reversal of 139521457 is 754125931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 754125931 = 13 ⋅58009687.

It can be written as a sum of positive squares in 2 ways, for example, as 16777216 + 122744241 = 4096^2 + 11079^2 .

It is a cyclic number.

It is not a de Polignac number, because 139521457 - 2³ = 139521449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (139021457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1143558 + ... + 1143679.

It is an arithmetic number, because the mean of its divisors is an integer number (35452189).

Almost surely, 2^139521457 is an apocalyptic number.

It is an amenable number.

139521457 is a deficient number, since it is larger than the sum of its proper divisors (2287299).

139521457 is an equidigital number, since it uses as much as digits as its factorization.

139521457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2287298.

The product of its digits is 37800, while the sum is 37.

The square root of 139521457 is about 11811.9201233330. The cubic root of 139521457 is about 518.6571082134.

The spelling of 139521457 in words is "one hundred thirty-nine million, five hundred twenty-one thousand, four hundred fifty-seven".