139566391 has 4 divisors (see below), whose sum is σ = 139593384. Its totient is φ = 139539400.

The previous prime is 139566389. The next prime is 139566397. The reversal of 139566391 is 193665931.

139566391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 139566391 - 2¹ = 139566389 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 (139566397) 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, 3040 + ... + 16981.

It is an arithmetic number, because the mean of its divisors is an integer number (34898346).

Almost surely, 2^139566391 is an apocalyptic number.

139566391 is a deficient number, since it is larger than the sum of its proper divisors (26993).

139566391 is an equidigital number, since it uses as much as digits as its factorization.

139566391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26992.

The product of its digits is 131220, while the sum is 43.

The square root of 139566391 is about 11813.8220318405. The cubic root of 139566391 is about 518.7127814590.

The spelling of 139566391 in words is "one hundred thirty-nine million, five hundred sixty-six thousand, three hundred ninety-one".