981554591 has 4 divisors (see below), whose sum is σ = 981666312. Its totient is φ = 981442872.

The previous prime is 981554579. The next prime is 981554633. The reversal of 981554591 is 195455189.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 195455189 = 10607 ⋅18427.

It is a cyclic number.

It is not a de Polignac number, because 981554591 - 2¹⁰ = 981553567 is a prime.

It is a super-2 number, since 2×981554591² = 1926898830226354562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981554501) 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, 41441 + ... + 60666.

It is an arithmetic number, because the mean of its divisors is an integer number (245416578).

Almost surely, 2^981554591 is an apocalyptic number.

981554591 is a deficient number, since it is larger than the sum of its proper divisors (111721).

981554591 is a wasteful number, since it uses less digits than its factorization.

981554591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111720.

The product of its digits is 324000, while the sum is 47.

The square root of 981554591 is about 31329.7716397678. The cubic root of 981554591 is about 993.8133344337.

The spelling of 981554591 in words is "nine hundred eighty-one million, five hundred fifty-four thousand, five hundred ninety-one".