1389725721 has 32 divisors (see below), whose sum is σ = 2169868800. Its totient is φ = 876646800.

The previous prime is 1389725719. The next prime is 1389725731. The reversal of 1389725721 is 1275279831.

1389725721 is a `hidden beast` number, since 1 + 3 + 8 + 9 + 72 + 572 + 1 = 666.

It is not a de Polignac number, because 1389725721 - 2¹ = 1389725719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1389725731) 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 31 ways as a sum of consecutive naturals, for example, 743430 + ... + 745296.

It is an arithmetic number, because the mean of its divisors is an integer number (67808400).

Almost surely, 2^1389725721 is an apocalyptic number.

It is an amenable number.

1389725721 is a deficient number, since it is larger than the sum of its proper divisors (780143079).

1389725721 is a wasteful number, since it uses less digits than its factorization.

1389725721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3346 (or 3340 counting only the distinct ones).

The product of its digits is 211680, while the sum is 45.

The square root of 1389725721 is about 37279.0252152601. The cubic root of 1389725721 is about 1115.9456196765.

The spelling of 1389725721 in words is "one billion, three hundred eighty-nine million, seven hundred twenty-five thousand, seven hundred twenty-one".