981855391 has 4 divisors (see below), whose sum is σ = 1071114984. Its totient is φ = 892595800.

The previous prime is 981855377. The next prime is 981855409. The reversal of 981855391 is 193558189.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 193558189 = 11 ⋅17596199.

It is a cyclic number.

It is not a de Polignac number, because 981855391 - 2²⁹ = 444984479 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981855491) 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, 44629780 + ... + 44629801.

It is an arithmetic number, because the mean of its divisors is an integer number (267778746).

Almost surely, 2^981855391 is an apocalyptic number.

981855391 is a deficient number, since it is larger than the sum of its proper divisors (89259593).

981855391 is a wasteful number, since it uses less digits than its factorization.

981855391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89259592.

The product of its digits is 388800, while the sum is 49.

The square root of 981855391 is about 31334.5718177224. The cubic root of 981855391 is about 993.9148429733.

The spelling of 981855391 in words is "nine hundred eighty-one million, eight hundred fifty-five thousand, three hundred ninety-one".