81577373 has 4 divisors (see below), whose sum is σ = 86376060. Its totient is φ = 76778688.

The previous prime is 81577361. The next prime is 81577381. The reversal of 81577373 is 37377518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 37377518 = 2 ⋅18688759.

It can be written as a sum of positive squares in 2 ways, for example, as 23406244 + 58171129 = 4838^2 + 7627^2 .

It is a cyclic number.

It is not a de Polignac number, because 81577373 - 2¹⁸ = 81315229 is a prime.

It is a super-2 number, since 2×81577373² = 13309735571162258, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81577373.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81577673) 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, 2399318 + ... + 2399351.

It is an arithmetic number, because the mean of its divisors is an integer number (21594015).

Almost surely, 2^81577373 is an apocalyptic number.

It is an amenable number.

81577373 is a deficient number, since it is larger than the sum of its proper divisors (4798687).

81577373 is a wasteful number, since it uses less digits than its factorization.

81577373 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4798686.

The product of its digits is 123480, while the sum is 41.

The square root of 81577373 is about 9032.0193201742. The cubic root of 81577373 is about 433.7004824613.

The spelling of 81577373 in words is "eighty-one million, five hundred seventy-seven thousand, three hundred seventy-three".