139878391 has 4 divisors (see below), whose sum is σ = 140410512. Its totient is φ = 139346272.

The previous prime is 139878383. The next prime is 139878419. The reversal of 139878391 is 193878931.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 139878391 - 2³ = 139878383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (139878301) 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, 265666 + ... + 266191.

It is an arithmetic number, because the mean of its divisors is an integer number (35102628).

Almost surely, 2^139878391 is an apocalyptic number.

139878391 is a deficient number, since it is larger than the sum of its proper divisors (532121).

139878391 is an equidigital number, since it uses as much as digits as its factorization.

139878391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 532120.

The product of its digits is 326592, while the sum is 49.

The square root of 139878391 is about 11827.0195315642. The cubic root of 139878391 is about 519.0990204380.

The spelling of 139878391 in words is "one hundred thirty-nine million, eight hundred seventy-eight thousand, three hundred ninety-one".