139949921 has 4 divisors (see below), whose sum is σ = 142244244. Its totient is φ = 137655600.

The previous prime is 139949891. The next prime is 139949923. The reversal of 139949921 is 129949931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129949931 = 23 ⋅5649997.

It can be written as a sum of positive squares in 2 ways, for example, as 71656225 + 68293696 = 8465^2 + 8264^2 .

It is a cyclic number.

It is not a de Polignac number, because 139949921 - 2²² = 135755617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (139949923) 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, 1147070 + ... + 1147191.

It is an arithmetic number, because the mean of its divisors is an integer number (35561061).

Almost surely, 2^139949921 is an apocalyptic number.

It is an amenable number.

139949921 is a deficient number, since it is larger than the sum of its proper divisors (2294323).

139949921 is an equidigital number, since it uses as much as digits as its factorization.

139949921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2294322.

The product of its digits is 157464, while the sum is 47.

The square root of 139949921 is about 11830.0431529221. The cubic root of 139949921 is about 519.1874897271.

The spelling of 139949921 in words is "one hundred thirty-nine million, nine hundred forty-nine thousand, nine hundred twenty-one".