81554391 has 8 divisors (see below), whose sum is σ = 120821360. Its totient is φ = 54369576.

The previous prime is 81554387. The next prime is 81554411. The reversal of 81554391 is 19345518.

It is not a de Polignac number, because 81554391 - 2² = 81554387 is a prime.

It is a super-2 number, since 2×81554391² = 13302237382761762, 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 (81554791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1510240 + ... + 1510293.

It is an arithmetic number, because the mean of its divisors is an integer number (15102670).

Almost surely, 2^81554391 is an apocalyptic number.

81554391 is a deficient number, since it is larger than the sum of its proper divisors (39266969).

81554391 is a wasteful number, since it uses less digits than its factorization.

81554391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3020542 (or 3020536 counting only the distinct ones).

The product of its digits is 21600, while the sum is 36.

The square root of 81554391 is about 9030.7469790710. The cubic root of 81554391 is about 433.6597512297.

The spelling of 81554391 in words is "eighty-one million, five hundred fifty-four thousand, three hundred ninety-one".