81577369 has 4 divisors (see below), whose sum is σ = 81595444. Its totient is φ = 81559296.

The previous prime is 81577361. The next prime is 81577381. The reversal of 81577369 is 96377518.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 57957769 + 23619600 = 7613^2 + 4860^2 .

It is a cyclic number.

It is not a de Polignac number, because 81577369 - 2³ = 81577361 is a prime.

It is a super-2 number, since 2×81577369² = 13309734265924322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81577361) 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, 4069 + ... + 13405.

It is an arithmetic number, because the mean of its divisors is an integer number (20398861).

Almost surely, 2^81577369 is an apocalyptic number.

It is an amenable number.

81577369 is a deficient number, since it is larger than the sum of its proper divisors (18075).

81577369 is an equidigital number, since it uses as much as digits as its factorization.

81577369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18074.

The product of its digits is 317520, while the sum is 46.

The square root of 81577369 is about 9032.0190987398. The cubic root of 81577369 is about 433.7004753728.

The spelling of 81577369 in words is "eighty-one million, five hundred seventy-seven thousand, three hundred sixty-nine".