155857391 has 4 divisors (see below), whose sum is σ = 156109800. Its totient is φ = 155604984.

The previous prime is 155857349. The next prime is 155857417. The reversal of 155857391 is 193758551.

It is a happy number.

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 155857391 - 2¹⁰ = 155856367 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 (155857991) 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, 125276 + ... + 126513.

It is an arithmetic number, because the mean of its divisors is an integer number (39027450).

Almost surely, 2^155857391 is an apocalyptic number.

155857391 is a deficient number, since it is larger than the sum of its proper divisors (252409).

155857391 is an equidigital number, since it uses as much as digits as its factorization.

155857391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252408.

The product of its digits is 189000, while the sum is 44.

The square root of 155857391 is about 12484.2857625096. The cubic root of 155857391 is about 538.1571738971.

The spelling of 155857391 in words is "one hundred fifty-five million, eight hundred fifty-seven thousand, three hundred ninety-one".