139421521 has 4 divisors (see below), whose sum is σ = 140775232. Its totient is φ = 138067812.

The previous prime is 139421519. The next prime is 139421549. The reversal of 139421521 is 125124931.

139421521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 139421521 - 2¹ = 139421519 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 139421521.

It is not an unprimeable number, because it can be changed into a prime (139421551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 676701 + ... + 676906.

It is an arithmetic number, because the mean of its divisors is an integer number (35193808).

Almost surely, 2^139421521 is an apocalyptic number.

It is an amenable number.

139421521 is a deficient number, since it is larger than the sum of its proper divisors (1353711).

139421521 is a wasteful number, since it uses less digits than its factorization.

139421521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1353710.

The product of its digits is 2160, while the sum is 28.

The square root of 139421521 is about 11807.6890626405. The cubic root of 139421521 is about 518.5332445958.

The spelling of 139421521 in words is "one hundred thirty-nine million, four hundred twenty-one thousand, five hundred twenty-one".