139821 has 16 divisors (see below), whose sum is σ = 215040. Its totient is φ = 79920.

The previous prime is 139813. The next prime is 139831. The reversal of 139821 is 128931.

It is not a de Polignac number, because 139821 - 2³ = 139813 is a prime.

139821 is a lucky number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 139791 and 139800.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 139821.

It is not an unprimeable number, because it can be changed into a prime (139801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 516 + ... + 738.

It is an arithmetic number, because the mean of its divisors is an integer number (13440).

2¹³⁹⁸²¹ is an apocalyptic number.

139821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

139821 is a deficient number, since it is larger than the sum of its proper divisors (75219).

139821 is a wasteful number, since it uses less digits than its factorization.

139821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256.

The product of its digits is 432, while the sum is 24.

The square root of 139821 is about 373.9264633588. The cubic root of 139821 is about 51.9028016649.

The spelling of 139821 in words is "one hundred thirty-nine thousand, eight hundred twenty-one".