139724221 has 16 divisors (see below), whose sum is σ = 174794368. Its totient is φ = 108734400.

The previous prime is 139724201. The next prime is 139724227. The reversal of 139724221 is 122427931.

It is a cyclic number.

It is not a de Polignac number, because 139724221 - 2⁷ = 139724093 is a prime.

It is the 11821-st Hogben number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (139724227) by changing a digit.

It is a nontrivial repunit in base 11820.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7035 + ... + 18136.

It is an arithmetic number, because the mean of its divisors is an integer number (10924648).

Almost surely, 2^139724221 is an apocalyptic number.

It is an amenable number.

139724221 is a deficient number, since it is larger than the sum of its proper divisors (35070147).

139724221 is a wasteful number, since it uses less digits than its factorization.

139724221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25252.

The product of its digits is 6048, while the sum is 31.

The square root of 139724221 is about 11820.5000317245. The cubic root of 139724221 is about 518.9082382509.

The spelling of 139724221 in words is "one hundred thirty-nine million, seven hundred twenty-four thousand, two hundred twenty-one".