81554573 has 4 divisors (see below), whose sum is σ = 85100448. Its totient is φ = 78008700.

The previous prime is 81554569. The next prime is 81554633. The reversal of 81554573 is 37545518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81554573 - 2² = 81554569 is a prime.

It is a super-2 number, since 2×81554573² = 13302296754424658, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81554503) 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, 1772903 + ... + 1772948.

It is an arithmetic number, because the mean of its divisors is an integer number (21275112).

Almost surely, 2^81554573 is an apocalyptic number.

It is an amenable number.

81554573 is a deficient number, since it is larger than the sum of its proper divisors (3545875).

81554573 is a wasteful number, since it uses less digits than its factorization.

81554573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3545874.

The product of its digits is 84000, while the sum is 38.

The square root of 81554573 is about 9030.7570557512. The cubic root of 81554573 is about 433.6600738202.

The spelling of 81554573 in words is "eighty-one million, five hundred fifty-four thousand, five hundred seventy-three".